Studies - Breast Cancer

Delayed Birth Increases Risk of Breast Cancer; Induced Abortion is a Risk Factor for Preterm Births

Consider “Alice” who is pregnant for the first time at age 20 years. Would it be all right if Alice terminates this pregnancy and eventually has a first birth, at say, age 35 years? Stein and Susser would have to agree that, in general, such a decision is fine and healthy. I would argue that when Alice signs the consent form for the termination, she should be informed that delaying her pregnancy by 10 to 15 years substantially increases her relative breast cancer risk.

A 15-year delay in first full-term pregnancy increases relative breast cancer risk by 67.3% (absolute increase: 8.41%).2 Krieger wrote, “Conversely, early age at first full-term pregnancy consistently has emerged as the strongest protective factor [against breast cancer].”3
A 10-year delay in age at first full-term pregnancy by terminating earlier pregnancy increases relative breast cancer risk by 41% (absolute increase: 5.13%).


Barbara Luke and Judith Lumley, recognized authorities in the field of premature births, have identified induced abortion as a risk factor for prematurity.4,5 In her book on preventing prematurity, Luke discusses her belief that induced abortion leads to an “incompetent cervix,” 4 whereas Lumley believes that induced abortion causes intrauterine infection and subsequent prematurity.5 In 1992, Daling et al reported that women with previous induced abortions had a 140% elevated risk of intra-amniotic infection in subsequent pregnancies.6 To my knowledge, at least 16 studies show that previous induced abortions boost risk of prematurity.5,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21 Therefore, an elective procedure that Stein and Susser sanction increases the risks of both breast cancer and subsequent preterm birth.22


In both the United States and Canada, induced abortion is legally considered to be an elective medical procedure.23 For an elective procedure, even remote—1 in 100,000—risks of serious adverse side effects must be disclosed on consent forms. The risks of breast cancer and preterm birth addressed in this letter are orders of magnitude higher than 1 in 100,000 and should be disclosed on abortion clinic consent forms.2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23 It is a scandal that these risks are not currently disclosed on such consent forms.


Both medical practitioners and medical researchers have an ethical obligation to, “first, do no harm.” For medical researchers, this means not turning a blind eye to serious adverse side effects. How does this specifically apply to the medical field in the current context? About 2 years ago, Stephanie Carter, at the age of 17 years, had an induced abortion performed by Dr Charles Benjamin. On the consent form, the words “breast cancer” did not appear.24 Stephanie Carter has filed a lawsuit against Dr Benjamin alleging, in part, that Benjamin did not inform her of the breast cancer risks of that induced abortion.24

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2. Trichopoulos D, Hsieh CC, MacMahon B, et al. Age at any birth and birth and breast cancer risk. Int J Cancer 1983;31: 701-704. [PubMed]
3. Krieger N. Exposure, susceptibility, and breast cancer risk: a hypothesis regarding exogenous carcinogens, breast tissue development, and social gradients, including black/white differences, in breast cancer incidence. Breast Cancer Res Treat 1989;13: 205-223. [PubMed]
4. Luke B. Every Pregnant Woman’s Guide To Preventing Premature Birth. New York: Times Books; 1995.
5. Lumley J. The association between prior spontaneous abortion, prior induced abortion and preterm birth in first singleton births. Prenat Neonat Med 1998;3: 21-24.
6. Daling JR, Krohn MA. Miscarriage or termination in the immediately preceding pregnancy increases the risk of intra-amniotic infection in the following pregnancy. Am J Epidemiol 1992;136: 1013 [SER Abstracts].
7. Zhou W, Sorensen HT, Olsen J. Induced abortion and subsequent pregnancy duration. Obstet Gynecol 1999;94: 948-953. [PubMed]
8. Pickering RM, Forbes JF. Risk of preterm delivery and small-for-gestational age infants following abortion: a population study. Br J Obstet Gynaecol 1985;92: 1106-1112. [PubMed]
9. Michielutte R, Ernest JM, Moore ML, et al. A comparison of risk assessment models for term and preterm low birthweight. Prev Med 1992;21: 98-109. [PubMed]
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11. Lieberman E, Ryan KJ, Monson RR, Schoenbaum SC. Risk factors accounting for racial differences in the rate of premature birth. N Engl J Med 1987;317: 743-748. [PubMed]
12. Lang JM, Lieberman E, Cohen A. A comparison of risk factors for preterm labor and term small-for-gestational-age birth. Epidemiology 1996;7: 369-376. [PubMed]
13. Mueller-Heubach E, Guzick DS. Evaluation of risk scoring in a preterm birth prevention study of indigent patients. Am J Obstet Gynecol 1989;160: 829-835. [PubMed]
14. Shiono PH, Klebanoff MA. Ethnic differences in preterm and very preterm delivery. Am J Public Health 1986;76: 1317-1321. [PMC free article] [PubMed]
15. Pantelakis SN, Papadimitriou GC, Doxiadis SA. Influence of induced and spontaneous abortions on the outcome of subsequent pregnancies. Am J Obstet Gynecol 1973;116: 799-805. [PubMed]
16. Van Der Slikke JW, Treffers PE. Influence of induced abortion on gestational duration in subsequent pregnancies. Br Med J 1978;1: 270-272 [PMC free article] [PubMed]
17. Richardson JA, Dixon G. Effect of legal termination on subsequent pregnancy. Br Med J 1976;1: 1303-1304. [PMC free article] [PubMed]
18. Pickering RM, Deeks JJ. Risks of delivery during 20th to the 36th week of gestation. Int J Epidemiol 1991;20: 456-466. [PubMed]
19. Koller O, Eikhom SN. Late sequelae of induced abortion in primigravidae. The outcome of the subsequent pregnancies Acta Obstet Gynecol Scand 1977;56: 311-317. [PubMed]
20. Bognar Z, Czeizel A. Mortality and morbidity associated with legal abortions in Hungary, 1960-1973. Am J Public Health 1976;66: 568-575. [PMC free article] [PubMed]
21. Papaevangelou G, Vrettos AS, Papadatos C, Alexiou D. The effect of spontaneous and induced abortion on prematurity and birthweight. J Obstet Gynaecol Br Commonw 1973;80: 418-422. [PubMed]
22. Rooney B. Racism, poverty, abortion, and other reproductive outcomes. Epidemiology 2000;11: 740-742. [PubMed]
23. Robertson GB, Picard EI. Legal Liability of Doctors and Hospitals in Canada. Scarborough, Ontario, Canada: Carswell; 1996.
24. Brind J. Case filed by PA teen for NJ abortion with no ABC warning. Abortion-Breast Cancer Quarterly Update 2000;4: 3, 8.
[West J Medicine, June 2001, 174(6): 385-386, Letter to editor, ]