Impact on Later Pregnancies
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"Role of Induced Abortion in Secondary Infertility," J.R. Daling, L.R. Spadoni, I. Emanuel, Obstet Gynecol 57: 59,1981.
- A case-control study of married couples diagnosed as having secondary infertility at the University of Washington Hospital in 1976-78 found that women with a history of prior induced abortion had a 1.31 relative increased risk of secondary infertility (0.71-2.43, 95% C.I.), which was not statistically significant, compared with controls.
"Induced abortions, miscarriages and tobacco smoking as risk factors for secondary infertility," A. Tzonou, et al, J. Epidemiology and Comm. Health 47:36,1993.
- In a case-control study by the Harvard Schools of Public Health and the University of Athens, of women in Athens, Greece in 1987-88, the occurrence of either induced abortions or spontaneous abortions independently and significantly increased the risk of subsequent secondary infertility. The logistic progression adjusted relative risks was 2.1 (1.1-4.0, 95% C.I.) for secondary infertility when there was 1 previous abortion and 2.3 (1.0-5.5, 95% C.I.) when there were 2 previous abortions. The adjusted relative risk of tobacco smoking for secondary infertility was 3.0 (1.3-6.8, 95% C.I.) compared to non- smokers. Secondary infertility was defined as  patient had a previous conception;  patient was married;  husband had a normal semen analysis and  patient had been trying become pregnant for at least 18 months.
"The effect of induced abortion on subsequent fertility," P Frank et al, Br J Obstetrics and Gynecology 100:575, 1993.
- In a follow-up analysis of British women who had an induced abortion compared to women whose last pregnancy had a natural outcome, it was found that at the end of 12 months 89% of the abortion group had achieved a pregnancy compared to 93.3% on the non-abortion group which approached statistical significance
"Contraception after abortion and postpartum," H. Vorherr, Am.J. Obstet. Gynecol. 117(7):1002, Dec. 1, 1973
- A study at the University of New Mexico reported that in 5-10% of healthy nonpostpartum women (apparently post abortion women) anovulary cycles are observed.
"Short and Long-term Results of Pregnancy by Different Methods, E.I," Sotnikova, Acta Medica Hungarica 43 (2): 139-143 (1986).
- A Russian study of 560 women undergoing abortion by curettage, prostaglandin and vacuum aspiration found that one-third of the women had serious ovarian dysfunction 3-5 years post-abortion. Ovarian dysfunction was six times more observed than genital inflammations. Post-abortion complications were more frequent in women with a late menarche and with a history of genital inflammation. Instrumental abortion has more short-term complications (12%) than the other methods.
"Risk factors for uterine fibroids among women undergoing tubal sterilization," CR Chen et al, Am J Epidemiol 153(1): 20-26, 2001.
- Parous women were at reduced risk for uterine fibroids while elective abortion did not reduce the risk for uterine fibroids compared to nulliparous women.
"Risk factors for uterine fibroids: reduced risk associated with oral contraceptives," RK Ross et al, British Medical Journal 293:359, August 9, 1986.
- The risk of fibroids decreased consistently with increasing number of term pregnancies. There was no reduction in risk with incomplete pregnancies (induced abortion or spontaneous abortion) but a slight, but not significant increase in risk of fibroids.
Gestational Trophoblastic Disease
- Gestational trophbloastic neoplasia includes complete hydatidiform mole, invasive mole, and choriocacinoma. Choriocarcinoma is malignant and therefore is considered a form of cancer. According to a 1986 U.S. study the incidence of choriocarcinoma is about 1 in 24,000 pregnancies. The incidence of molar pregnancy is reported to be 1 per 1500 live births and it is potentially life threatening. According to pregnancy-related deaths of U.S. women compiled by the CDC for 1987-90, 6 women died from molar pregnancy.
"Risk Factors for Gestational Tropoblastic Neoplasia," ML Messerli et al, Am J Obstet Gynecol 153:294, 1985.
- A case-control study of gynecologic and reproductive risk factors for gestational trophoblastic neoplasia among Baltimore area women from 1975-1982 found that there was a higher mean incidence of induced abortions or spontaneous abortions among cases compared to controls, while women having at least one term pregnancy or one live birth provided a protective effect.
"A Case-Control Study from the People's Republic of China," LA Brinton et al, Am J Obstet Gynecol 161:121, 1989.
- A case-control study of Chinese women with complete hydatidiform mole found that a history of a term birth was associated with a statistically significant reduced risk of 0.6 , while a history of one induced abortion had a nonsignificant increased relative risk of 1.2, and a history of two or more induced abortions had a statistically significant increased risk of 2.8, compared to women with no history of induced abortion.
"Risk factors for complete molar pregnancy from a case-control study," RS Berkowitz et al, Am J Obstet Gynecol 152:1016-1020, 1985.
- A Massachusetts study of women with molar pregnancy matched with parous controls without molar pregnancy found that there was a 8-fold increased risk for molar pregnancy when the prior pregnancy was an induced abortion.
"Case-Control Study of Gestational Choriocarcinoma," JD Buckley et al, Cancer Research 48:1004-1010, 1981.
- A multi-centered study of women with gestational choriocarcinoma matched women by year of pregnancy, age at pregnancy, and geographical residence found that an induced abortion preceding the choriocarcinoma was a risk factor while a live birth was protective against choriocarcinoma. The authors concluded that the most important factor for choriocarcinoma is the nature of the preceding pregnancy.
"Pregnancy Termination, Choricarcinoma Presenting as a Complication of Elective First Trimester Abortion," F.A. Lyon and L.L. Adcock, Minnesota Medicine, October, 1980, pp. 733-735.
- A case report is presented in which metastatic gestational disease was detected at a routine two-week post abortion examination due to the incomplete removal of fetal remains.
"Choriocarcinoma Following M.T.P," A.S. Gupta, K. Mukherjee, S. Chowdhury, J. Indian Medical Association 82(7): 255, July, 1984.
- Two cases are presented where choricarcinoma developed in Calcutta, India hospital following induced abortion.
Hypertension (High-Blood Pressure)
"Pregnancy-Related Mortality in the United States. 1987-1990," C.J. Berg et. al., Obstetrics and Gynecology 88:161,1996.
- According to data published by the Centers for Disease Control for 1987-1990, 256 U.S. women died from complications due to pregnancy-induced hypertension out of a total number of 1453 pregnancy-related deaths during this period which represented 17.6% of all pregnancy-related deaths.
"The relationship between abortion in the first pregnancy and development of pregnancy-induced hypertension in the subsequent pregnancy," DM Strickland et al.,Am. J. of Obstet. Gynecol. 154: 146,1986.
- In a study of 24,646 women who delivered at Parkland Memorial Hospital during 1977-80, the incidence of pregnancy-induced hypertension was 25.4% in primiaravid women, 22.3% among women whose only previous pregnancy terminated in abortion (either spontaneous or induced), and only 10% among women who carried two or more successive pregnancies to viability. Additional completed pregnancies after the first pregnancy did not confer any additional protective effect. It was concluded that the protective effect from abortion was small compared to a completed pregnancy.
"A Multivariate Analysis of Risk Factors for Preclampsia," B. Eskenazi et. al., JAMA 266: 231,1991.
- A study of women who gave birth at Northern California Kaiser Permanent Hospital in 1984-85 found that women with a history of therapeutic abortion were 2.16 times more likely to have preclampsia (1.18-3.96, CI 95%) compared to no therapeutic abortion history. In contrast to induced abortion, a previous spontaneous abortion was found to have a protective effect (0.48, 0.24-0.95, CI 95%.)
"Pregnancy-Induced Hypertension in North Carolina," 1988 and 1989, D.A. Savitz, J. Zhang, Am. J. Public Health 82 (5): 675,1992.
- A study of birth records in North Carolina during 1988-1989 examined the risk for pregnancy-induced hypertension (PIH) and found that the overall risk of PIH was 43.1 per 1000 births. Having had one child (Parity 1) was protective against PIH compared to no children (Parity 0) (0.4, 0.3-0.4, CI 95%). Blacks and whites were found to be a virtually equal risk. Mothers aged 35 or older were at increased risk compared to mothers aged 20-34 (1.6,1.4-1.8, CI 95%).
"Pre-eclampsia in second pregnancy," D.M. Campbell, I. MacGillivray, R. Carr-Hill, Br. J. Obstet. Gynaecol. 92: 131, Feb. 1985.
- In a comprehensive and well-designed study of 29/851 women in Aberdeen, Scotland with first or second pregnancies, found that the incidence of proteinuric pre-clampsia after early abortion, which was either spontaneous or induced (separately studied) was similar to the population incidence in a first pregnancy (7.6% v. 5.6%). Only a pregnancy of 37 weeks gestation or more was likely to offer protection against pre-eclampsia in a second pregnancy. The incidence of proteinuric pre-eclampsia or mild pre-eclampsia in the next pregnancy after an induced abortion was 7.6% and 26.7% respectively in contrast to 1.9% and 17.0% where there was a viable first pregnancy prior to the second pregnancy.
"Risk of Ectopic Pregnancy and Previous Induced Abortion," C Tharaux-Deneux et al, Am J Public Health 88(3): 401, 1998.
- A French case-control study found that among women with no previous ectopic pregnancy, women with one previous induced abortion had a statistically significant increased risk of 1.4, while women with two or more previous induced abortions had a statistically significant increased risk of 1.9 for ectopic pregnancy compared to women with no previous induced abortion. Ed Note: This study is possibly the only one which did not include women with a previous ectopic pregnancy. Previous ectopic pregnancy greatly increases the likelihood of another ectopic pregnancy and is a confounding factor. Failure to control for this variable would tend to make it appear that there was a lesser risk or perhaps no statistically increased risk of ectopic pregnancy from induced abortion.
"Risk Factors for Ectopic Pregnancy. A Population-Based Study," P.A. Marchbanks et. al, J. American Medical Association 259(12): 1823, March 25, 1988.
- A case-control study at Mayo Clinic from 1935-1982, using univariate analysis found a 2.5 relative risk for ectopic pregnancy from induced abortion (1.02-6.1, 95% CI and a 4.0 relative risk from pelvic inflammatory disease (2.2-7.2, 95% CI. The Multivariate risk from induced abortion was 2.1 (0.8-5.9, 95% CI) and 3.3 (1.6-6.6, 95% CI for pelvic inflammatory disease.)
"An Updated Protocol for Abortion Surveillance With Ultrasound and Immediate Pathology," S.R. Goldstein, M. Danon, C. Watson, Obstet. Gynecol. 83: 55-58,1994.
- In a study of 674 women who presented for first trimester abortion ultrasonography determined that 2.5% were 13 weeks or more despite bimanual examinations and the last menstrual period suggesting 12 or fewer weeks. The incidence of ectopic pregnancy was 0.58% and tubal pregnancy was 0.29% with an overall incidence of 0.87% using HCG and ultrasonography on-site testing.
"Induced abortions and risk of ectopic pregnancy," F. Parazzini et al. Human Reproduction 10(7): 1841,1995.
- An Italian case-control study found that the multivariate risk of ectopic pregnancy for any induced abortion was 2.9,1.6-5.3, 95% CI. The risk increased with the number of induced abortions both with obstetric and non-obstetric controls.
"Ectopic Pregnancy Surveillance United States, 1970 - 1987," K. Nederof, H. Lawson, A. Saftlas, H. Atrash and E. Finch, Morbidity and Mortality Weekly Report 39(SS-4) December, 1990.
- Ectopic pregnancy has risen from 17,800 cases in 1970 to 88,000 hospitalized cases in 1987. From 1970 - 1987 approximately 877,400 cases have been reported among U.S. women 15-44 years. Thirty women were reported to have died from ectopic pregnancy in 1987. Although the cause of ectopic pregnancy is unknown, it has been attributed to alteration in tubal motility, hormonal release and anatomical changes such as scarring. Scarring may be caused by acute and chronic salpingitis.
"Ectopic Pregnancy and Prior Induced Abortion," A.Levin, S. Schoenbaum, P. Stubblefield, S. Zimicki, R. Monson and K. Ryan, American Journal of Public Health, 72(3):253- 256, March 1982.
- This study found a relationship between the number of prior induced abortions and the risk of ectopic pregnancy: the crude relative risk of ectopic pregnancy was 1.6 for women with one prior induced abortion and 4.0 for women with two or more prior induced abortions; however, use of multivariate techniques to control confounding factors reduced the relative risks to 1.3 and 2.6, respectively. The analysis suggests that induced abortion may be one of several risk factors for ectopic pregnancy, particularly for women who have had abortions plus pelvic inflammatory disease or multiple abortions.
"Pathogenesis of Tubal Pregnancy," J. Niles, and J. Clark, American Journal of Obstetrics and Gynecology, 105 (8): 1230-1234, December 15,1969.
- A pathologic review was made of 436 ectopic pregnancies treated at a hospital over a 10 1/2 year period. Only about 40 percent of the cases studied had a histologic diagnosis of chronic inflammatory disease. Fifty-eight percent of the cases had no demonstrable histologic abnormality to produce an ectopic nidation, suggesting a functional pathogenesis. From the literature, the study noted factors which theoretically and logically could play a more important role in ectopic nidation than that of chronic pelvic inflammatory disease. They are (1) iatrogenic factors, (2) hormonal, (3) retrograde menstruation, (4) functional causes, and (5) the conceptus. Various studies were cited.
"Etiology of Ectopic Pregnancy: A New Concept," Joseph G. Asherman, Obstetrics and Gynecology, 16(6):619-624, December 1955.
- Out of 325 patients with a history of ectopic pregnancy, 181 had one or more abortions, either spontaneous or induced. Of those, 135 were induced and 67 were spontaneous abortions. Twenty-one of the 181 women had both induced and spontaneous abortions. The study found that functional disturbances of the propelling mechanism of the tubes are to blame rather than pathologic changes in the tubes themselves. The movements of the tubal musculature (an inner circular and an outer longitudinal layer) are as dependent upon the hormonal as upon the nervous system. Any disturbance in the neurodendocrine balance is likely to bring about a change in the normal functioning of the tubes and may result in infertility or tubal pregnancy, depending on the severity of the disturbance. Why are induced abortions twice as damaging as spontaneous ones, when the intervention is the same for both? There is only one difference between the two kinds of abortion, the impact of psychic trauma. Any abortion, whether spontaneous or induced, may be the source of bitter frustration which will deepen with the passage of time if the yearning for motherhood is not satisfied. In induced abortion, however, an additional emotional factor is at work, leading, in the course of time, to a guilt complex. These make the inner tension of such women much higher than those experiencing spontaneous abortion.
"Ectopic Pregnancy and Myoma Uteri: Tetragenic Effects and Maternal characteristics," E. Matsunaga, and K. Shiota, Teratology 21: 61-69 (1980).
- Fetal malformations were found in 11.6 percent of ectopic pregnancies compared with lesser percentages for controls. Maternal smoking and drinking were cited as causes.
"Induced Abortion and Ectopic Pregnancy in Subsequent Pregnancies," C.S. Chung, R.G. Smith, P.G. Steinoff, and M.P. Mi, American Journal of Epidemiology 115(6): 879- 887 (1982).
- There was a clear association between the presence of post-abortion infection or retained parts and a 5 fold increase in ectopic pregnancy compared to uninfected women.
"Etiology of Cervical Pregnancy," D. Dicker, D. Feldbeg, N. Samuel, J.A. Goldman, The J. of Reproductive Medicine 30(1): 25, Jan., 1985.
- An association was found between cervical pregnancy and prior induced abortion.
"Ectopic Pregnancy and First Trimester Abortion," L.A. Schonberg, Obstetrics and Gynecology 49(1) (Supp): 735, Jan. 1977.
- Among a total of 41/753 first trimester abortions done over a 4 year period at two Planned Parenthood Centers in New York City from 1971-1975 only 11 verified cases of ectopic (tubal) pregnancy were discovered; 3 patients had a rupture of their tubal pregnancy immediately following suction curettage, 6 patients had rupture of the tube from 1-19 days after suction curettage. Only two unruptured ectopic gestations were diagnosed. Ed. Note: In 1975 the ectopic pregnancy rate was 7.6 per 1000 pregnancies (live births, induced abortions and ectopic pregnancy). Based on that rate PP should have discovered about 312 ectopic pregnancies.
"Ectopic Pregnancy in Relation to Previous Induced Abortion," T.R. Daling, W.H. Chow, N.S. Weiss, B.J. Metch and R. Suderstrom, Journal of the American Medical Association,253(7): 1005-1008, February 15,1985.
- Women who have one induced abortion showed virtually no excess risk of ectopic pregnancy. (RR=1.4). For women with two or more abortions, the relative risk was 1.8. In the author's opinion, it remains unresolved whether having a legal induced abortion imparts an excess risk of ectopic pregnancy. Nonetheless, the results relating to the group of women having two or more abortions (RR of 1.8 and 2.6 in two of the studies) are worrisome.
"Risk Factors For Ectopic Pregnancy: A Case-Control Study in France, with Special Focus on Infectious Factors," J. Coste, N. Job-Spira, H. Fernandez, E. Papiernik, A. Spira, Am.J. Epidemiology 133(9): 839, May, 1991.
- A case-control study in 1988 in seven Paris area hospitals found a 1.6 relative risk of ectopic pregnancy where there was prior induced abortion (1.1-2.3,95% C.I.). If adjustments were made for age, smoking and pelvic inflammatory disease the association disappeared. Ed. Note: Adjustments for PID and smoking should not have been made as induced abortion is implicated.
"Ectopic Pregnancy Critical Analysis of 139 Cases," M. Faith Kamsheh, Minnesota Medicine, February 1983, pp. 83-86.
- Between 1975 and 1981, the number of ectopic pregnancies at Fairview Hospital more than doubled. Ectopic pregnancy is responsible for 10 percent of all maternal deaths. Patients who are infertile, did not use birth control, or who have a history of recent abortion or menstrual extraction, of PID, of IUD or recent removal of IUD or a history of previous tubal sterilization, tubal pregnancy, tubal reconstruction, and abdominal surgery have a high index of suspicion.
"Ectopic Pregnancy Case Study," Clinton A. Turner, Perspectives and Problems in OB/GYN, January 1985, Published for Stuart Pharmaceuticals by Communications in Med. Div. of Cahners Pub. Co., 475 Park Avenue S., New York, NY 10016.
- The most alarming risk factor of all for ectopic pregnancy is a prior history of ectopic pregnancy. The risk of ectopic pregnancy in a patient who has had a prior one is approximately 20 times greater than that of a general population. A previous history of PID or a prior abortion were listed as risk factors for ectopic pregnancy.
"Ectopic Pregnancy - A New Surgical Epidemic," Louis Weinstein, M. Morris, D. Dotters and C.D. Christian, Obstetrics and Gynecology, 61(6): 698-701, June 1983
- Between March 1972 and September 1981,154 patients were diagnosed for ectopic pregnancy at the University of Arizona. Currently, the incidence of ectopic pregnancy at the University of Arizona is one in 45 live births. 22.7 percent reported one or more previous therapeutic abortions; 14.9 percent reported a history of previous PID. Pelvic inflammatory disease is believed to be the major etiologic factor in the rising rate of ectopic pregnancy.
"Ectopic Pregnancy in the United States: 1970-1983," H. Atrash, Morbidity and Mortality Weekly Report 35(22S) Aug. 1986.
- 70,000 women were hospitalized for ectopic pregnancy in the U.S. in 1983, resulting in 70,000 fetal deaths. Ectopic pregnancy accounted for 12.8 percent of all maternal deaths in the U.S. in 1983. In 1985 black women continued to have a 3.5 times higher risk of death from ectopic pregnancy. Teenage black women have a 6.2 times higher risk than white teenagers.
"A 21-Year Survey of 654 Ectopic Pregnancies," James L. Breen, American Journal of Obstetrics and Gynecology, 106(7):1004-1019, April 1,1970
- A review of the patients' operations or therapy seemed to substantiate that antecedent inflammatory disease recorded in 185 patients is a prime etiologic factor in ectopic pregnancy. A history of previous antibiotic therapy in 345 patients also implied therapy of pelvic inflammatory disease. A previous ectopic pregnancy in 45 patients (6.9 percent) or a previous tubal ligation in four patients (0.6 percent) may have been potentially edologic.
"An Overview of Infectious Aunts of Salpingitis, Their Biology and Recent Advances in Methods of Detection," P-A Mardh, American Journal Obstetrics and Gynecology, 138(7):933- 951 Part 2, December 1,1980.
- In salpingitis, it is believed that anaerobic bacteria often gain entrance to the tubes as secondary invades from the lower genital tract in patients whose tubes have been damaged with sexually transmitted disease agents. In such secondary infections, both anaerobic and facultatively anaerobic bacteria can be demonstrated. Endogenous tubal infections may occur in hosts whose genital organs have been "compromised" by gynecologic surgery, curettage, legal or illegal abortion, or various diagnostic procedures. In the hospital catchment region of Lund such "iatrogenic" cases constitute approximately 15 percent of all salpingitis patients. See"Epidemiology. Etiology and Prognosis of Acute Salpingitis - a study of 1.457 laparoscopically verified cases," L. Westrom and P-A Mardh, in Non-gonococcal Urethritis and Related Infections, D. Hobson and K. Holmes, eds.,(Washington, D.C.: American Society for Microbiology, 1977) 84-90.
"Repeat Ectopic Pregnancy: A Study of 123 Consecutive Cases," Jack G. Hallatt, American Journal of Obstetrics and Gynecology, 122(4): 520, June 15,1975.
- This study concludes the principal etiology of ectopic pregnancy as healed salpingitis which may have been gonorrheal, post-abortal or puerperal. These infections are readily controlled with antibiotics but fusion of the plical of the endosalpinix is a sequelae. These tubal adhesions subsequently trap the developing embryo.
"Chlamydia Trachomatis Infections in the United States, What Are They Costing Us?" A. Eugene Washington, R.E. Johnson, L.L. Sanders, Journal of the American Medical Association, 257(15): 2070-2072, April 17,1987.
- It is estimated that each year 402,200 episodes of chlamydial PID occur, leading to 13,900 ectopic pregnancies and 280 deaths.
Sexually Transmitted Diseases. K.K. Holmes, P.A. Mardh, P.F. Sparling, O.J. Wiesner (1984) 630.
- Women in the post-salpingitic state have a seven- to tenfold risk for ectopic pregnancy, compared with women who never had the disease.
Placenta Previa/Aburuptio Placentae/Retained Placenta
"The Association of Placenta Previa with History of Caesarean Delivery and Abortion: A Meta Analysis," CV Anath et al, Am J Obstet Gynecol 177: 1071, 1997.
- A review of 12 studies by researchers at the Robert Wood Johnson Medical School found that there was a strong association between a previous induced abortion and a higher risk of placenta previa among U.S. women.
"Placenta Previa in Relation to Induced and Spontaneous Abortion: A Population- Based Study," V.M. Taylor et al., Obstet. Gynecol. 82: 88-91,1993
- A study of birth certificate data among Washington state white women during 1984-1987 found that women who reported one or more induced abortions were 1.28 times more likely to have a pregnancy complicated by placenta previa which was statistically significant.
"Induced Abortion: A Risk Factor For Placenta Previa," J.M. Barrett, F. H. Boehm, A.P. Killam, AmJ. Obstet Gynecol 141:769,1981.
- A study at Vanderbilt University in 1979-80 found that 3.8% of the women with a history of induced abortion had placenta previa. If it was the first delivery since an induced first trimester induced abortion, the incidence of placenta previa was 4.6% compared to an overall percentage of 0.9%.
"Long-term sequelae following legally induced abortion," E.B. Obel, Danish Medical Bulletin 27(2): 61, April, 1980.
- A Danish study compared women who's previous pregnancy was terminated by a legal induced abortion (group 1), with women whose previous pregnancy had ended in a spontaneous abortion or still birth (group 2), women whose previous pregnancy ended in a live birth (group 3), and women with no previous pregnancies. The study found that an induced abortion increases the risk of bleeding in a subsequent pregnancy compared with women with previous deliveries as well as women with no previous pregnancies. Delivery following a legally induced abortion had a greater tendency of retention of placenta or placental tissue than in a woman with no previous pregnancies. A legally induced abortion complicated by pelvic inflammatory disease may reduce a woman's fertility.
"Abruptio placentae and placenta previa: Frequency, perinatal mortality and cigarette smoking," R.L. Naeye, Obstet Gynecol. 55:701-704,1980.
- Abruptio placentae and placenta previa was greater in women who smoked than in those who had never smoked. Perinatal mortality showed similar differences. Placenta previa became more frequent with age and with number of years smoked. Mothers who stopped smoking had a 23% lower frequency of abruptio placentae and a 33% lower frequency of placenta previa than women who continued to smoke during pregnancy.
"The conservative aggressive management of placenta previa," D.B. Cotton, J.A. Read, R.I.T. Paul, E.J. Quilligan, AmJ. Obstet.Gynecol. 137:687,1980.
- A California study of 173 cases of placenta previa during 1975-78 found that a history of prior abortion, previous placenta previa or prior cesarean section enhanced the risk of developing placenta previa. The complications associated with placenta previa included fetal malpresentation (breech or transverse lie), cord prolapse and premature rupture of the membranes.
"Late Sequelae of Induced Abortion: Complications and Outcome of Pregnancy and Labor," S. Harlap and M. Davies, Am. J. Epidemiology 102(3): 217,1975.
- A prospective study of 11,057 pregnancies of West Jerusalem mothers found that 0.3% of women reporting no previous induced abortions had placenta previa compared to 0.8% of women reporting one or more induced abortions according to crude rates. Standardized rates showed no statistical significance (0.4% vs. 0.5%).
"Risk Factors for Abruptio Placentae," M.A. Williams et. al.. Am. J. Epidemiology134: 965-972, 1991
- A prior induced abortion was 1.3 times more likely to result in abruptio placente in a subsequent pregnancy compared to no prior induced abortion.
"The Impact of Multiple Induced Abortions on the Outcome of Subsequent Pregnancy," A. Lopes et. al., Aust NZ Obstet. Gynaecol. 31(1): 41,1991
- In a study of Chinese women with two previous induced abortions and a subgroup of women with three or more previous induced abortions compared to age-matched primigravidas, the incidence of retained placenta was significantly higher among women with two prior induced abortions (2.9%) or three or more prior induced abortions (7.0%) compared with the control group (0.4%). Postpartum hemhorrage was also higher in women with two prior induced abortions (1.6%) or among women with three or more induced abortions (3.5%) compared with controls (0.8%).
Subsequent Miscarriage, Premature Birth or Low Birth Weight
Effect of Induced Abortions on Early Preterm Births and Adverse Perinatal Outcomes. J Obstet Gynaecol Can 2013;35(2):138–143.
- Abstract excerpt
- Results: A total of 17 916 women were included in the study. Of these 2276 (13%) had undergone one prior induced abortion, and 862 (5%) had undergone two or more prior induced abortions. Women with a prior induced abortion were more likely to be smokers and to consume alcohol, and were less likely to be married. Women who reported one prior induced abortion were more likely to have premature births by 32, 28, and 26 weeks; adjusted odds ratios were 1.45 (95% CI 1.11 to 1.90), 1.71 (95% CI 1.21 to 2.42), and 2.17 (95% CI 1.41 to 3.35), respectively. This association was stronger for women with two or more previous induced abortions. Prior induced abortion was associated with an increased requirement for tocolysis in subsequent pregnancies, but there was no association between prior induced abortions and NICU admission, intrapartum fever, and preterm premature rupture of membranes.
- Conclusion: Our study showed a significant increase in the risk of preterm delivery in women with a history of previous induced abortion. This association was stronger with decreasing gestational age.
- Editor's translation: One prior abortion increased the risk of premature delivery at 26 weeks or earlier by at least 41% up to 235%.
Repeated Abortion Affects Subsequent Pregnancy Outcomes in BALB/c Mice Lv F, Xu X, Zhang S, Wang L, Wang N, He B, Wang J. PLoS One. 2012;7(10):e48384. doi: 10.1371/journal.pone.0048384. Epub 2012 Oct 31.
- Induced medical abortion using mifepristone (RU 486)in mice was associated with elevated rates of miscarriage, placental dysfunction, with reduced expression of tissue factor (TF) and genes encoding proteins involved in metabolic functions relevant to pregnancy, such as 11β-hydroxysteroid dehydrogenase 1/2 (11β-HSD1/2) and glucocorticoid receptor (GR). Reduced expression was also observed for platelet endothelial cell adhesion molecule-1 (CD31) and vascular endothelial growth factor (VEGF). In offspring from subsequent pregnancies, genes involved in lipid metabolism, which may enhance key lipid transcription factors, such as PPARA and PPARG, as well as GR/11β-HSD1, were downregulated in the liver. In addition, the sperm motility of the F1 males reduced.
- This study is of particular note because it is the only known study using animals. Abortion procedures have generally been implemented on human beings without prior test on animals.
Contribution of Risk Factors to Extremely, Very and Moderately Preterm Births – Register- Based Analysis of 1,390,742 Singleton Births. Raisanen S, Gissler M, Saari J, Kramer M, Heinonen S (2013) PLoS ONE 8(4): e60660.
The study reported significantly elevated rates of extremely preterm, very preterm, and moderately preterm births for pregnancies among women with a history of abortion (adjusted odds ratios being 1.28, 1.16, 1.07, respectively, and for women who smoked ( 1.21, 1.23, 1.15.) The authors concluded that smoking was the most important risk, but they were unaware and did not discuss the link between abortion and elevated rates of smoking.
Reproductive outcomes following induced abortion: a national register-based cohort study in Scotland. Bhattacharya S, Lowit A, Bhattacharya S, Raja EA, Lee AJ, Mahmood T, Templeton A. BMJ Open. 2012 Aug 6;2(4). pii: e000911. doi: 10.1136/bmjopen-2012-000911. Print 2012.
- OBJECTIVE: To investigate reproductive outcomes in women following induced abortion (IA).
- DESIGN: Retrospective cohort study.
- SETTING: Hospital admissions between 1981 and 2007 in Scotland.
- PARTICIPANTS: Data were extracted on all women who had an IA, a miscarriage or a live birth from the Scottish Morbidity Records. A total of 120 033, 457 477 and 47 355 women with a documented second pregnancy following an IA, live birth and miscarriage, respectively, were identified.
- OUTCOMES: Obstetric and perinatal outcomes, especially preterm delivery in a second ongoing pregnancy following an IA, were compared with those in primigravidae, as well as those who had a miscarriage or live birth in their first pregnancy. Outcomes after surgical and medical termination as well as after one or more consecutive IAs were compared.
- RESULTS: IA in a first pregnancy increased the risk of spontaneous preterm birth compared with that in primigravidae (adjusted RR (adj. RR) 1.37, 95% CI 1.32 to 1.42) or women with an initial live birth (adj. RR 1.66, 95% CI 1.58 to 1.74) but not in comparison with women with a previous miscarriage (adj. RR 0.85, 95% CI 0.79 to 0.91). Surgical abortion increased the risk of spontaneous preterm birth compared with medical abortion (adj. RR 1.25, 95% CI 1.07 to 1.45). The adjusted RRs (95% CI) for spontaneous preterm delivery following two, three and four consecutive IAs were 0.94 (0.81 to 1.10), 1.06 (0.76 to 1.47) and 0.92 (0.53 to 1.61), respectively.
- CONCLUSIONS: The risk of preterm birth after IA is lower than that after miscarriage but higher than that in a first pregnancy or after a previous live birth. This risk is not increased further in women who undergo two or more consecutive IAs. Surgical abortion appears to be associated with an increased risk of spontaneous preterm birth in comparison with medical termination of pregnancy. Medical termination was not associated with an increased risk of preterm delivery compared to primigravidae.
[http://www.ncfpc.org/FNC/1305-FNC-Spring13-Abortion%27sImpactOnPrematurity2.pdf Abortion’s Impact on Prematurity: Closing the Knowledge Gap] Martin McCaffrey, M.D.. Family North Carolina, 2013
- A good summary of the literature.
Results of study presented at European Society of Human Reproduction and Embryology (ESHRE) conference in 2011 reported that women with a history of induced abortion were 33% more likely to have their next pregnancy delivered prematurely, and 44% more likely to give birth extremely prematurely, before 34 weeks. The study was led by Dr. Siladitya Bhattacharya, and examined the outcomes of the second pregnancies of 170,000 women who had previously had an abortion and 458,000 women undergoing their first pregnancies.
Induced Abortion and Risk of Later Premature Births. B Rooney and BC Calhoun, Journal of American Physicians and Surgeons 8(2):46-49, 2003.
- This study summarizes 49 studies which have demonstrated a statistically significant risk in premature births among women with prior induced abortions.
"Obstetric Complications and Risk for Severe Psychopathology in Childhood" J Autism and Developmental Disorders (2001;31:279-285 ) Eaton WW, Mortensen PB, Thomsen PH, Frydenberg M.
- Children born to women with prior history of induced abortion had 72% higher relative risk of later being diagnosed as mentally retarded, and a 40% greater risk of being diagnosed with a learning disorder, and a 47% risk of being diagnosed with some other psychological disorder.
Prenatal and perinatal risk factors for autism. J Perinat Med. 1999;27(6):441-50. Burd L, Severud R, Kerbeshian J, Klug MG.
- Abortion and low birth weight are significantly associated with increased risk of autism in subsequent born children.
"Invited commentary: maternal effects in preterm birth--effects of maternal genotype, mitochondrial DNA, imprinting, or environment?" Little J. Am J Epidemiol. 2009 Dec 1;170(11):1386-7.
- (ABSTRACT) Preterm birth is an important public health problem. A wide range of risk factors has been investigated, of which the strongest established is a woman's previous history of preterm birth. In this issue of the Journal, Boyd et al. (Am J Epidemiol. 2009;170(11):1358-1364) and Svensson et al. (Am J Epidemiol. 2009;170(11):1365-1372), using data on singleton livebirths from national birth registers linked with multigeneration databases, found evidence that maternal genetic factors impact on the risk for preterm birth, whereas paternal and probably fetal genetic factors do not. Possible caveats include missing information, the range of maternal risk factors included in the analyses, possible misclassification of these risk factors, and possible vertical transmission of microbial flora or behaviors from mother to daughter. Weinberg and Shi (Am J Epidemiol. 2009;170(11):1373-1381) build on the evidence regarding potential mechanisms underlying the heritability of preterm birth from these 2 and other studies, to evaluate the comparative ability of different study designs to distinguish among these potential mechanisms. These studies have different strengths, and a portfolio of studies of different designs and with more detailed phenotyping than previously done will be needed to probe further the etiology of preterm birth and thereby provide tools for its control.
- (COMMENT) Little identifies "previous abortion" as a factor in pre-term birth, citing "Swingle HM, Colaizy TT, Zimmerman MB, et al. Abortion and the risk of subsequent preterm birth: a systematic review with meta-analyses. J Reprod Med. 2009;54(2):95–108."
"Induced termination of pregnancy and low birthweight and preterm birth: a systematic review and meta-analyses" Shah PS, Zao J. British J Ob Gyn 2009 Oct; 116(11):1425-1442.
- Background History of induced termination of pregnancy (I-TOP) is suggested as a precursor for infant being born low birthweight (LBW), preterm (PT) or small for gestational age (SGA). Infection, mechanical trauma to the cervix leading to cervical incompetence and scarred tissue following curettage are suspected mechanisms.
- Objective To systematically review the risk of an infant being born LBW/PT/SGA among women with history of I-TOP.
- Selection criteria: Studies reporting birth outcomes to mothers with or without history of induced abortion were included from Medline, Embase, CINAHL and bibliographies of identified articles were searched for English language studies.
- Data collection and analyses: Two reviewers independently collected data and assessed the quality of the studies for biases in sample selection, exposure assessment, confounder adjustment, analytical, outcome assessments and attrition. Meta-analyses were performed using random effect model and odds ratio (OR), weighted mean difference and 95% confidence interval (CI) were calculated.
- Main results: Thirty-seven studies of low–moderate risk of bias were included. A history of one I-TOP was associated with increased unadjusted odds of LBW (OR 1.35, 95% CI 1.20–1.52) and PT (OR 1.36, 95% CI 1.24–1.50), but not SGA (OR 0.87, 95% CI 0.69–1.09). A history of more than one I-TOP was associated with LBW (OR 1.72, 95% CI 1.45–2.04) and PT (OR 1.93, 95% CI 1.28–2.71). Meta-analyses of adjusted risk estimates confirmed these findings.
- Conclusions: A previous I-TOP is associated with a significantly increased risk of LBW and PT but not SGA. The risk increased as the number of I-TOP increased.
"Previous abortion and the risk of low birth weight and preterm births." Brown JS Jr, Adera T, Masho SW. J Epidemiol Community Health. 2008 Jan;62(1):16-22.
- Abortions increase the risk of low birth weight by three fold and the risk of premature birth two fold. According to the authors, the effect is causal. "The accruing risk, says co-author Tilahun Adera at Virginia Commonwealth University, suggests that termination of pregnancy is a true cause of low birth weight and preterm birth rather than a variable associated with such conditions. 'It's not just an association,' he says. 'The risk of premature birth increases with the increasing number of abortions.'"
- OBJECTIVE: To investigate the association between previous abortion and low birth weight (LBW) and preterm birth (PB). METHOD: The study examined live, singleton births using data from the United States Collaborative Perinatal Project. Over 45,000 single-child live births from 1959 to 1966 were examined. Logistic regression was used to control for obstetric and medical history, and lifestyle and demographic factors. RESULT: Compared with women with no history of abortion, women who had one, two and three or more previous abortions were 2.8 (95% CI 2.48 to 3.07), 4.6 (95% CI 3.94 to 5.46) and 9.5 (95% CI 7.72 to 11.67) times more likely to have LBW, respectively. The risk for PB was also 1.7 (95% CI 1.52 to 1.83), 2.0 (95% CI 1.73 to 2.37) and 3.0 (95% CI 2.47 to 3.70) times higher for women with a history of one, two and three or more previous abortions, respectively. CONCLUSION: Previous abortion is a significant risk factor for LBW and PB, and the risk increases with the increasing number of previous abortions. Practitioners should consider previous abortion as a risk factor for LBW and PB.
"Cost consequences of induced abortion as an attributable risk for preterm birth and its impact on informed consent" Calhoun B, Shadigian E, Rooney B. Journal of Reproductive Medicine Oct. 2007
- 31.5% of preterm births are attributable to a history of induced abortion and that the initial neonatal hospital costs for treating preterm births until release from the hospital cost the nation over $1.2 billion per year. (With 1.2 million abortions per year, this translates to additional health care costs $1000 per abortion.) Moreover, this cost estimate does not include additional costs associated with follow-up care or with lifetime treatment costs associated with cerebral palsy (1096 cases per year) attributable to excess premature births attributable to abortion.
"Abuse During Pregnancy: Effects on Maternal Complications and Birth Weight in Adult and Teenage Women," B. Parker et al., Obstet. Gynecol. 84: 323,1994
- A study of poor African-American, Hispanic and white urban female residents from 1990- 1993 in Baltimore, Maryland and Houston, Texas found that physical and sexual abuse during pregnancy occured among one in five teens and one in six adult women. Abused women were significantly at risk for pregnancy complications as well as drug or alcohol use.
"Induced Abortion as a Risk Factor for Subsequent Fetal Loss," C Infante-Rivard and R Gauthier, Epidemiology 7:540, 1996.
- In a Canadian case-control study of fetal losses and prior reproductive history in a Montreal obstetrical care facility during 1987-91, it was found that compared to women with no previous pregnancies (1.0), women with one prior pregnancy and no induced abortions had a non-significant (1.03) increased relative risk; women with two prior pregnancies and no induced abortions had a non-significant (0.71) reduced relative risk; women with one prior pregnancy and one prior induced abortion had a non-significant (1.41) increased relative risk; and women with two prior pregnancies and two prior abortions had a statistically significant (4.43) increased relative risk of fetal loss.)
"Induced Abortion and Subsequent Pregnancy Duration," W Zhou et al, Obstetrics and Gynecology 94:948, 1999.
- A Danish study using national registries found a statistically significant 1.96 increased relative risk of preterm delivery for women with pregnancy intervals exceeding 12 months with one vacuum aspiration abortion, 2.62 increased relative risk for two vacuum aspiration abortions, and 2.16 for three vacuum aspiration abortions compared to women with other pregnancy outcomes and no induced abortion history.
"Risk factors associated with preterm and early preterm birth, univariate and multivariate analysis of 106,345 singleton births from the 1994 statewide perinatal survey of Bavaria," JA Martius et al, Eur J Obstet Gynecol Reprod Biol 80(2): 183-189, 1998.
- In a mulitvariate analysis, an increased risk of early preterm birth was associated with previous induced abortion (OR 1.8, 1.57-2.13 ,95% CI)
"A Comparison of Risk Factors for Preterm Labor and Term Small for Gestational Age Birth," JM Lang et al, Epidemiology 7:369, 1996.
- A study at the Boston Hospital for Women controlled for the effects of 23 factors on preterm labor and fetal growth retardation. Compared to women with no previous induced abortion (1.0) , women with one induced abortion had a non-significant (1.1) increased relative risk of preterm labor; women with two previous induced abortions had a statistically significant increased relative risk of (1.9); and women with three or more induced abortions had a statistically significant increased relative risk of (3.6).
"Very and moderate preterm births: are the risk factors different," ? Pierre-Yves Ancel et al, Br J Obstet Gynaecol 106: 1162-1170, 1999.
- A case-control study in 15 European countries found that a previous first trimester abortion increased the risk of very preterm births (22-32 weeks) by 86% and increased the risk of moderate preterm births (33-36 weeks) by 58%. A previous second trimester abortion increased the risk of very preterm births by 267% and increased the risk of moderate preterm births by 133% compared to controls (37 weeks or more).
"The epidemiology of pre-term birth," Judith Lumley, Bailliere's Clinical Obstetrics and Gynaecology 7(3): 477, Sept. 1993
- A study of more than 300,000 first singleton births in Victoria, Australia from 1986-1990 found that 6.5 per 1000 births were 20-27 gestational weeks where the woman had one prior induced abortion compared to 10.3 per 1000 births (two prior induced abortions) and 23.1 per 1000 births (three or more prior induced abortions). The rate of pre-term births at 32-36 gestational weeks was 54.1 per 1000 births where the women had one prior induced abortion, 78.7 per 1000 births where women had two prior induced abortions and 120.1 per 1000 births where women had three or more prior induced abortions. For purposes of analysis women who had experienced both induced and spontaneous abortions were excluded.
"Association of Induced Abortion with Subsequent Pregnancy Loss," A. Levin, S. Schoenbaum, R. Monson, P. Stubblefield, and K. Ryan Journal of American Medical Association243:2495(1980).
- This study compared prior pregnancy histories of two groups of women, one having a pregnancy loss up to 28 weeks gestation and the other having a full-term delivery. Women who had two or more prior induced abortions had a twofold to threefold increase in first-trimester spontaneous abortions (miscarriage) between 14 to 20 and 20 to 27 weeks. The increased risk was present for women who had legal induced abortions since 1973. It was not explained by smoking status, history of prior spontaneous loss, prior abortion method, or degree of cervical dilation. No increased risk of pregnancy loss was detected among women with a single induced prior abortion.
"A Comparison of Risk Assessment Models for Term and Preterm Low Birthweight," R Michielutte et al, Preventive Medicine 21:98-109, 1992.
- A large North Carolina study found that two or more previous induced abortions increased the risk of low birth weight in subsequent birth by 42%; one or more second trimester abortions increased the risk of low birth weight in subsequent birth weight by 78%; a previous live birth reduced the risk of low birth weight compared to no previous live birth.
"The association with multiple induced abortions with subsequent prematurity and spontaneous abortion," L.H. Roht, H. Aoyama, G.E. Leinen, Acta Obstet Gynaecol, Japan 23:140- 145,1976.
- Induced abortion was associated with higher prematurity and spontaneous abortion rates in later pregnancies. Women who had 2 or more abortions had a 2-3 times increased risk of miscarrying a pregnancy.
"Late sequelae of induced abortion in primigravidae," 0. Koller and S.N. Eikhom, Acta Obstet. Gynecol. Scand, 56:311 (1977).
- The total rates of later abortions and infants with low birth weight below 2500 grams was higher in women with a previous induced abortion than in women whose previous pregnancy ended in a spontaneous abortion or delivery.
"Influence of induced abortion on gestational duration in subsequent pregnancies," J.W. Vander Slikke and P.A. Treffers, British Medical Journal I, 270-272 (1978).
- A Dutch study compared the outcome of subsequent pregnancies of 265 women who had at least one abortion in a previous pregnancy with the outcome in an age matched group of 265 with no abortion history. 6.4% women with abortion history had deliveries prior to the 32nd week of gestation compared to only 1.2% of the women with no abortion history.
"Late Sequelae of Induced Abortion: Complications and Outcome of Pregnancy and Labor," S. Harlap and M. Davies, AmJ. Epidemiology 102(3):217 (1975).
- This study found that birthweight less than 2500 grams as well as a birthweight less than 2000 grams were significantly more frequent in an obstetric history of one or more induced abortions than in a group of patients without a history of induced abortion; 6.3% v. 4.7% below 2500 grams and 2.3% v. 1.4% below 2000 grams. The differences in birthweight were found to be due to preterm delivery and not to growth retardation. It was not clear whether the induced abortions in all cases immediately preceded the current pregnancy. Most abortions in this study were thought to have been illegal.
"Delayed reproductive complications after induced abortion," K. Dalaker, S.M. Lictenberg, G. Okland, Acta Obstel Gynecol Scand. 58:491-494,1979.
- A Norwegian study compared 619 women who had their last pregnancy terminated by abortion to an age and parity matched group of women who continued the pregnancy to delivery. Among those who had not been pregnant previously the complications rate was 25.5% in the abortion group compared to 13.2% in the control which was statistically significant. Complications included first and second trimester abortion (miscarriage), cervical incompetence, pre-term delivery, ectopic pregnancy and sterility. After women had one or two live births there was no statistical significance between the two groups.
"Second-trimester abortion after vaginal termination of pregnancy," C.S.W. Wright, S. Campbell, J. Beazley, Lancet 1,1278-1279 (1972).
- A British study compared the outcome of the subsequent pregnancy in 91 women who had induced abortions with a control group of 3233 women in which no induced abortions had occurred. In the group with prior induced abortion 9% had second trimester abortions (miscarriage) compared to only 0.9% in the group with no induced abortions.
"Gestation, Birth-Weight and Spontaneous Abortion in Pregnancy After Induced Abortion," Report of the Collaborative Study by World Health Organization Task Force on Sequelae of Abortion. The Lancet I, 142-145, January 20,1979.
- In a study of 7228 European women from 8 cities the reduction in mean birth-weight associated with cigarette smoking varied from 120-146 grams. Low birth weight in the pregnancy after induced abortion by vacuum aspiration was 5.4% to 6.1% compared with 2.9%-4.7% for prior live birth or 3.7% if no previous pregnancy. Short gestation (258 days) was 4.7%-5.7% in the pregnancy after abortion with vacuum aspiration compared to 2.0%-3.9% for prior live birth or 2.4%-3.0% for no previous pregnancy. No significant differences between groups were found with respect to mid-trimester spontaneous abortions.
"Low Birth Weight in Relation to Multiple Induced Abortions," M.T. Mandelson, C.B. Maden. J.R. Daling, AmJ. Public Health 82(3):391-394, March, 1992.
- In a Washington State study of 6541 white women who delivered their first child between 1984-87, 4.4% of women with no reported abortions had low birth weight babies (2500 grams or less) compared to 5.7% of women reporting 1 abortion, 7.7% of women reporting 2 abortions, 7.1% of women reporting 3 abortions, and 9.6% of women reporting 4 or more abortions. These differences approached statistical significance.
"Effects of legal termination on subsequent pregnancy," J.A. Richardson and G. Dixon, British Medical Journal 1,1303-1304 (1976).
- This study observed more first-trimester abortions (miscarriages), second trimester abortions and premature deliveries (less than 37 week amenorrhea) in a group of 211 patients whose previous pregnancy was artificially interrupted than they observed in a parity matched group of 147 women whose previous pregnancy resulted in a spontaneous abortion. Ninety-one of the 211 women became pregnant again within 1 year despite good contraceptive advice.
"A study on the effects of induced abortion on subsequent pregnancy outcome," C. Madore, W.E. Haws, F. Many, A.C. Hexter, AmJ. Obstet. Gynecol 139:516-521,1981.
- A California case-control study of 2081 women who had one or more induced abortions matched with 4098 controls without a history of abortion found that a prior induced abortion had a relative risk of 1.45 (1.06-1.99, 95% C.I.) of pregnancy failure (ectopic pregnancy, spontaneous abortion, fetal or neonatal death). Smokers had a relative risk of 1.85, (1.11-3.10, 95% C.I.) of pregnancy failure.
"Impact of Abortion on Subsequent Fecundity," Carol J. Hogue, Clinics in Obstetrics and Gynecology 13(1): 95, March, 1986
- Comments of the author:
- Compared to women who have previously delivered the risk of low birth weight is elevated for women delivering for the first time after an induced abortion by vacuum aspiration.
- Studies of first-trimester spontaneous abortion following induced abortion have been seriously flawed.
- Women who choose to have their first pregnancy terminated by abortion are at no increased risk of failing to conceive at a later date unless the abortion is complicated by infection leading to pelvic inflammatory disease. Women whose first pregnancy is terminated by vacuum aspiration are at no increased risk of subsequent ectopic pregnancy unless the abortion is complicated by pre-existing C. Trachomatis or post- abortion infection.
- More research is needed before it is clear whether multiple induced abortions carry an increased risk of adverse pregnancy outcomes.
"Risks of Preterm Delivery and Small For Gestational Age Infants Following Abortion: A Population Study," R. Pickering and J. Forbes, British Journal of Obstetrics and Gynecology, 92:1106-1112, Nov. 1985.
- Concludes that the relative risk of preterm delivery is significantly increased following abortion. "Late Sequelae of Induced Abortion: Complications and Outcome of Pregnancy and Labor," S. Harlap and A. Davies, American Journal of Epidemiology, 102(3):217- 224,1975. There was a significant increase in the frequency of low birth weight, compared to births in which the mother has no history of previous abortion.
"Pregnancy Complications Following Legally Induced Abortion," Erik Obel, Acta Obstet. Gynecol. Scand., 58: 485-490(1979).
- The study could not demonstrate an increased frequency of low birth weight among women whose previous pregnancy had been terminated by legal abortion, but did find that the rate of deliveries before 37 weeks gestation increased with the number of induced abortions.
"Prospective Study of Spontaneous Fetal Losses After Induced Abortions," S Harlap, P. Shioho, S. Ramcharan, H. Berendes, and F. Pellegrin New England Journal of Medicine, 301(13):677-681, September 27,1979.
- The relative risk of spontaneous fetal losses after induced abortion increased with the number of previous induced abortions and was not explained by the distribution of demographic and social variables.
"Habitual Abortion, Causes, Prevention and Management," William D. Schlaff, The Female Patient, 12:45-61 March, 1987.
- A number of reproductive tract infections have been suggested as possible causes of recurrent [spontaneous] abortion. Unfortunately, there seems to be no clear causative association between most of these infections and reported miscarriages. It is often difficult to differentiate the effect of an infection on the fetus from the maternal effect. Furthermore, studies examining the impact of infections on fetal wastage are frequently confounded by the presence of many other variables. Habitual abortion has been noted in approximately 15 percent of patients with intrauterine synexhiae [Asherman's syndrome]. This syndrome may be produced by intrauterine infection, puerperal dilatation and curettage or abortion.
World Health Organization, Special Program of Research, Development and Research Training in Human Reproduction: Seventh Annual Report. (Geneva: WHO, November 1978).
- A repeat abortion is associated with a two- to two and a half-fold increase in the rate of low birth weight and short gestation when compared with either one abortion or one live birth. Women were matched with women who had the same operative procedure. Cases and controls were matched also for age, smoking, institution and duration of gestation at entry into the study. See "Repeat Abortions Increase Risk of Miscarriage, Premature Birth and Low Birth-weight Babies" Family Planning Perspectives 11(1): 39- 40, Jan/Feb 1979
"Reproductive history and the risk of neonatal sepsis," M. Germain, M.A. Krohn, J.R. Daling, Pediatric and Perinatal Epidemiology 9: 48-58,1995.
- Induced abortion was associated with a statistically significant risk of neonatal sepsis in a subsequent pregnancy. The authors suggested that the procedures involved in induced abortion might produce a latent, sub-clinical infection until the next pregnancy, and then is transmitted to the newborn. Neonatal sepsis although it occurs in 1-10 cases per 1000 live births has a case fatality rate of 50-75% and is complicated by meningitis in 20-30% of cases and surviving children frequently have neurological defects.
"Prior pregnancy outcome and the risk of intraamniotic infection in the following pregnancy," MA Krohn et al, Am J Obstet Gynecol 178: 381-385, 1998.
- A Washington state study of hospital records found that the risk of intraamniotic infection was 4 times higher when the prior pregnancy outcome was an elective abortion compared to a prior birth of more than 20 weeks gestation.
Subsequent Fetal Malformation/Birth Defects
"Cardiac remodelling as a result of pre-term birth: implications for future cardiovascular diseaseBensley JG, Stacy VK, De Matteo R, Harding R, Black MJ. Eur Heart J. 2010 Aug;31(16):2058-66. Epub 2010 May 7.
- Premature delivery may impact heart development and increase vulnerability to cardiac disease.
"The Relationship Between Idiopathic Mental Retardation and Maternal Smoking During Pregnancy," C.D. Drew et. al. Pediatrics 97(4): 547, April, 1996.
- A study by researchers at Emory University suggested that maternal smoking may be a preventable cause of mental retardation in children.
"A Population-Based Study of Gastroschisis: Demographic, Pregnancy, and Lifestyle Risk Factors," C P. Torfs et all.. Teratology 50: 44-53,1994
- Urivariate analysis found a statistically significant risk of 1.96 of gastroschisis (an abdominal wall defect in newborns) where the mother had one or more elective abortions which was reduced to a 1.59 non-significant risk when adjusted for other reproductive variables.
"Hispanic Origin and Neural Tube Defects in Houston/Harris County. Texas, II Risk Factors." M.A. Canfield et al. Am. J. Epidemiology 143(1): 12,1996
- In a study of Hispanic women, any previous pregnancy termination or fetal loss was significantly associated with anencephaly in subsequent births in a final logistic regression model, 2.48,1.20-5.10, CI 95%). In contrast, with one or more live births in comparison with no previous births, there was a slight non-significant decrease in risk. The authors stated that " one of the factors for increased risk for anecephaly among Hispanic women might be elective pregnancy termination")
"Search for maternal factors associated with malformed human embryos: a prospective study," E. Matsunaga and K. Shiota, Teratology 21:323-331,1980.
- 3,474 malformed embryos from induced abortion were subjected to morphologic examination. 1.7% were malformed if there was no maternal genital bleeding; 4.9% were malformed with maternal genital bleeding; 15.8% were malformed if threatened abortion. Mothers of low parity showed an increased frequency of malformed embryos.
"Adverse effects on offspring of maternal alcohol abuse during pregnancy," Ouellette et al, New England Journal of Medicine 297:528-530,1977.
- A 1974-75 study at Boston City Hospital found that infants born to heavy drinkers had more than twice the congenital abnormality (32%) compared to abstainers (9%) or light drinkers (14%).
"Late Sequelae of Induced Abortion: Complications and Outcome of Pregnancy and Labor," S. Harlap and A.M. Davies, Am J. Epidemiology 102(3): 217,1975.
- A prospective study of 11,057 West Jerusalem mothers interviewed during pregnancy found that those who reported one or more prior induced abortions in the past were more likely to report bleeding in the 1st, 2nd. and 3rd. months of their pregnancy compared with women reporting no previously induced abortions. Women with prior abortions were less likely to have a normal delivery. In births following induced abortions, the relative risk of early neonatal death was doubled, while late neonatal deaths showed a 3 to 4 fold increase. Major and minor malformations were increased in the abortion group.
"Induced abortion and subsequent congenital malformations in offspring of subsequent pregnancies," M.B. Bracken, T.R. Holford, Am.J. Epidemiology 109(4):425-432,1979.
- A Connecticut case-control study during 1974-76 found that mothers with prior induced abortions had odds ratios above 1.0 with respect to the following specific congenital malformations of subsequently born children: Inquinal Hernia (OR 1.4, P=0.24); Anencephaly (OR 1.3, P=0.62); Poly-syndactyly (OR 2.7, P=0.02;); Downs (OR 1.5, P=0.46). Overall, white women delivering babies with congenital malformations were significantly less likely to report having had a previously induce abortion (OR 0.7, P=0.01) while black women who delivered were significantly more likely to have experienced a past induced abortion (OR 1.7, P=0.04).
"Ectopic Pregnancy and Myoma Uteric: Teratogenic Effects and Maternal Characteristics," E. Matsunaga and K. Shiota, Teratology 21:61-69,1980.
- In a Japanese study of 3614 well preserved human embryos derived from artificial termination of pregnancy, the frequency of malformed embryos recovered from ectopic pregnancies was 11.6% compared to 6.2% recovered from myomatous pregnancies and 3.3% from normally implanted pregnancies not complicated by myomas. Ed. Note: myoma means a benign neoplasm of the muscular tissue.