A number of studies done in the past 20 years indicate the existence of an increased risk of cervical and ovarian cancer where there has been a history of induced abortion. A higher incidence of rectal cancer may also be related to induced abortion, but further research is needed to explain this connection.(8-16)
A study published in the Medical Journal of Australia found that the incidence of cervical cancer increased amongst women with a history of previous induced abortion. (8) The researchers considered other possible causes but confirmed an association between a greater cancer risk and women who had undergone two or more abortions.
In 1993, La Vecchia and colleagues (9) established a cervical cancer risk following one induced abortion and reported that "...cervical cancer was directly associated with induced abortions." A second study by Schwartz and colleagues10 found a significant relationship between leiomyosarcoma (a cancerous tumour in the smooth muscle of the uterus) and a history of induced abortion.
Studies published in the British Journal of Cancer (11) and the Journal of the National Cancer Institute (12), found that women with one abortion face a relative risk of 2.3 of developing cervical cancer, compared to non-abortive women. Women with two or more abortions face a greatly increased relative risk of 4.92.
Mc Pherson wrote in the American Journal of Epidemiology (13) that for ovarian cancer, "a history of having had an induced abortion was a factor that remained statistically significant."
In 1992 Negri (14) et al conducted an Italian case-control study on the incidence of ovarian cancer among women who suffered incomplete pregnancies. They found that there was a positive relationship between ovarian cancer and abortion and that this risk rose with each abortion a woman underwent. Levin et al (14) a discovered similar results.
Many studies on abortion and subsequent cancers of the reproductive system, point to a theory that, carrying a pregnancy to term actually reduces a woman's risk of developing breast and other cancers. This idea is confirmed by Albrektsen's study,(15) published in May 1995 in the International Journal of Cancer, which determined that childbirth actually gives protection against cancers of the reproductive system. This protection occurs because of "a mechanical shed of malignant or pre-malignant cells at each delivery." This protection is not found in pregnancies ended by induced abortion.
Kvale and Heuch16 carried out a Norwegian study of 63,090 women and found 581 cases of colon cancer and 250 cases of rectal cancer. The authors report that "having had many abortions was associated with a high risk of colorectal cancer." The relative risk of both colon and rectal cancer ranged from 1.16 to 1.72. In other words the risk was up to 72% higher for women who had had abortions than for women who had carried their pregnancies to term.
Many publications list uterine perforation as a recognised complication of abortion. (17) The most common abortion techniques (Dilation & Curettage, Suction & Curettage) all carry a risk factor for uterine perforation. Researchers working in the field of post-abortion medical problems, as detailed below, agree that cervical or uterine damage continues to be a major ongoing complication that can even affect subsequent pregnancies.
A report conducted by Kaali and colleagues,(18) published in the American Journal of Obstetrics and Gynaecology found that "most traumatic uterine perforations are unreported or even unsuspected." Records from the 1970's showed that tears to the wall of the uterus occurred up to 6.4 times per 1000 abortions.
However, they conclude that such injuries are only detected during later gynaecological surgeries. Consequently, they now report the "true incidence of uterine perforations was...19.8 for every 1000 procedures."
M White et al (18) a also conducted a case-controlled study of uterine perforations and abortion. They record a perforation rate of 30.4 per 1000 procedures.
In reality, it is impossible to know the true rate of uterine perforation following induced abortion. However, there is reason to believe that post-abortion uterine damage frequently goes unreported or even unnoticed. A report published by Leibner entitled Delayed presentation of uterine perforation (19) confirms this; "Although uterine perforation with intra-abdominal injury is a well described complication of vacuum aspiration [suction] termination of pregnancy, most post-abortion perforations go undetected."
A significant consequence of perforation is that future pregnancies are affected. Uterine perforations produce scar tissue that can affect the implantation of a later embryo, making further childbearing more difficult. (20)
Nemec et al (21) reported that 6% of women who became pregnant after hysterotomy abortions (a similar procedure to a caesarean delivery) suffered rupture of their uterus. Substantial risk of rupture was found in 26% of these cases. More dangerously, uterine rupture is also one of the feared, and sometimes fatal, complications of prostagland in abortion.
Many studies have been completed which examine the relationship between cervical dilation and subsequent cervical damage, including laceration to the cervix. Cervical dilation is frequently used to facilitate abortion.
Molin et al (22) discuss the problem of reduced cervical resistance following first-trimester abortion. Cervical resistance is a stiffness in the neck of the uterus which makes it difficult to expand.
The study suggests that reduced cervical resistance has been associated with a reduction in the ability to continue subsequent pregnancies. Dilation up to 9 millimetres at the time of an abortion can lead to a fall in cervical resistance of 12.5% in patients, while dilation up to 11 millimetres can lead to a fall in cervical resistance of 66 to 67%.
F J Zlatnik (23) and colleagues concluded in their report that injury to the cervix could be a possible cause of later miscarriages. The study examined radiological inspections of the upper cervical canal in women with a history of premature deliveries. Zlatnik thus confirmed that induced abortion can cause the cervical muscles to be weakened and can therefore result in repeated pregnancy loss.
K Schulz (24) and colleagues wrote in The Lancet journal, that cervical injury is one of the most frequent complications of suction curettage abortion. They report a rate of cervical injury of up to 1.6 per 100 abortions. The authors also argue that fractures of the cervix may occur during forceful dilation of the cervix which can lead to cervical incompetence.
In a normal pregnancy, the placenta is attached to the supero-anterior (upper) wall of the uterus. In placenta praevia it implants in the inferior part of the uterus. Being near or over the cervix causes a blockage and leads to major complications for the mother.
Placenta praevia usually presents in the second and third trimester of pregnancy and can cause mortality to both unborn child and mother. It is one of the leading causes of excessive vaginal bleeding during pregnancy and usually necessitates a caesarean section.
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 praevia among U.S. women. (25)
A study by Barrett et al (26) at Vanderbilt University U.S.A found that a significant number of women whose pregnancies were complicated by placenta praevia had a history of induced abortion. Furthermore they found that women with a previous history of induced abortion were 7 to 15 times more likely to develop placenta praevia in a later pregnancy.
F Hutchinson (27) from the Cancer Research Centre in Seattle, evaluated the probability of placenta praevia being associated with a history of induced abortion by various methods. The study was conducted over two years and like the previous studies, concluded that the risk of placenta praevia is significantly increased by curettage abortions.
Cervical, Ovarian and Rectal Cancer
8. Brock K E, Berry G, Brinton L A, Kerr C, MacLenann R, Mock P A et al, "Sexual, reproductive and contraceptive risk factors for carcinoma-in-situ of the uterine cervix in Sydney," Medical Journal of Australia 1989 February 6; 150(3): 125-30
9. La Vecchia C, Negri E, Franceschi S, Parazzini F, "Long-term impact of reproductive factors on cancer risk," International Journal of Cancer 1993 January 21; 53: 215-9, p 127
10. Scwartz S M, Weiss N S, Daling J R, Newcomb P A, Liff J M , Gammon M D et al, "Incidence of histologic types of uterine sarcoma in relation to menstrual and reproductive history,” International Journal of Cancer, 1991 September 30;49 (3):362-7
11. Parazzini F et al "Risk of Invasive and Intraepithelial Cervical Neoplasia", British Journal of Cancer, 59:805-809
12. Stewart H l et al "Epidemiology of Cancers of the Uterine Cervix and Corpus, Breast and Ovary in Israel and New York City," Journal of National Cancer Institute, 37 (1):1-96
13. Mc Pherson C P, Sellers T A, Potter J D, Bostik R M, Folsom A R, "Reproductive factors and risk of endometrial cancer. The Iowa Women's Health Study,” American Journal of Epidemiology, 1996 June 5, 143 (12):1195-202 p 1195
14. Negri E et al., “Incomplete Pregnancies and Ovarian Cancer Risk,” Gynecologic Oncology 47:234-238, 1992
14a. Levin et al, "Association of Induced Abortion with Subsequent Pregnancy Loss,” Journal of the American Medical Association 243:2495,1980
15. Albrektsen G, Heuch I, Tretli S, Kvale G, "Is the risk of cancer of the corpus uteri reduced by a recent pregnancy? A prospective study of 765,756 Norwegian women,” International Journal of Cancer; 1995, May 16;61 (4):485-90, p 485
16. Kvale G, Heuch I, "Is the incidence of colorectal cancer related to reproduction? A prospective study of 63,000 women," International Journal of Cancer, 1991, February 1;47 (3):390-5, p 392
17. Mittal S, Misra S, "Uterine Perforation following Medical Termination of Pregnancy by Vacuum Aspiration," International Journal of Gynecology and Obstetrics, 23: 45-50 (1985)
18. Kaali et al, "The frequency and management of uterine perforations during first trimester abortions," American Journal of Obstetrics and Gynecology, 1989 August, 161(2):406-408
18a. White M et al, “A case-controlled study of uterine perforations documented at laparoscopy,” American Journal of Obstetrics and Gynaecology, 129:623, 1977
19. Leibner E C, "Delayed presentation of uterine perforation," Annals of Emergency Medicine, 1995 November; 26(5): 643-6
20. Frank P et al, "The Effect of Induced Abortion on Subsequent Fertility," British Journal of Obstetrics and Gynaecology 100: 575, 1993
21. Nemec D et al, "Medical Abortion Complications", Journal of Obstetrics and Gynecology; Vol 51 No 4 p 433-436
22. Molin et al, "Risk of damage to the cervix by dilation for first trimester induced abortion by suction aspiration," Gynecological and Obstetric Investigation 1993; 35(3) :152-4
23. Zlatnik F J et al, “Radiological appearance of the upper canal in women with a history of premature delivery,” Journal of Reproductive Medicine; 34(8):525-30
24. Schulz K et al, “Measures to prevent Cervical Injuries during suction curettage abortion,” The Lancet, May 28 1983, pp 1182-1184
25. Anath C V et al, "The Association of Placenta Praevia with History of Caesarean Delivery and Abortion: A Meta-Analysis," American Journal of Obstetrics and Gynecology 177: 1071, 1997
26. Barrett et al, "Induced Abortion: A risk factor for Placenta Praevia," American Journal of Obstetrics and Gynecology, 141:769, 1981
27. Hutchinson F, “The relationship between placenta praevia and history of induced abortion,” International Journal of Obstetrics and Gynecology, May 2003, 81(2):191-8
Pelvic Inflammatory Disease (PID) is a common condition in which infection in the lower female reproductive tract spreads to the upper tract. PID is a common cause of morbidity among women of reproductive age. Serious consequences of the disease include increased risk of infertility and ectopic pregnancy.
Chronic salpingitis (inflammation of the fallopian tubes) may follow an acute attack. Subsequent to inflammation, scarring and resulting adhesions may result. Due to blockage of the tubes by scar tissue, women with chronic salpingitis are at high risk of experiencing ectopic pregnancy. As previously discussed, this condition may be life-threatening.
Normally the cervix produces mucus which acts as a barrier to prevent pathogens (disease causing micro-organisms) from entering the uterus and moving upward to the tubes and ovaries. This barrier may be breached in two ways.
A sexually transmitted pathogen can invade the epithelial cells, alter them and gain entry. Otherwise organisms gain entry as a result of trauma to the cervix. Induced abortion is one of the conditions that can alter or weaken the normal epithelial cells making them more susceptible to infection.
The relationship between induced abortion and PID is well established. Levallois et al (39) report that "Pelvic infection is the most common complication of curettage abortion." Also Sorensen et al conclude in their report (40) that "Pelvic inflammatory disease is the most frequent complication of induced abortion...." They also refer to "...the high incidence of post-abortion PID with potential long-term risks of chronic pelvic pain, infertility and ectopic pregnancy."
Chlamydia trachomatis causes genital infections. According to Elizabeth Ring Cassidy and Ian Gentles, authors of Women's Health after Abortion,40a the abortion procedure can trigger a case of PID, but those post-abortion women who already have chlamydia are at far higher risk of PID than women who do not carry the organism.
Many women only discover that they are carriers of Chlamydia trachomatis pathogen when they develop post-abortion chlamydial pelvic inflammatory disease. By this stage it may be too late to avoid later fertility problems.
Most of the research on the association between abortion and PID has been conducted in Scandinavia and the UK. The research confirms an increase in the range of 6-30% for post-abortion infection.
Equally as worrying, the large Danish study by Nielson (41) found that even administering the antibiotic Ofloxacin before the abortion "did not significantly decrease the rate of post-abortion PID, neither among women with a previous history of PID, nor among those without previous PID."
Induced abortion is a trigger that can often move infection into the uterine cavity and produce effects that chlamydia by itself might not cause. For example Barbacci et al (42) found that 17.6% of patients with a history of abortion at the John Hopkins Hospital, Baltimore, U.S.A., tested positive for chlamydia. The doctors found "a significant correlation between the isolation of C trachomatis from the endocervical canal of patients undergoing abortion, and subsequent development of endometritis within two weeks of the abortion."
Sorensen and colleagues also determined that untreated women with chlamydial infection at the time of abortion had a risk as high as 72% of developing PID. They conclude that these women run the risk of "serious sequelae such as ectopic pregnancy." (40,43)
Pelvic Inflammatory Disease
39. Levallois et al, "Prophylactic antibiotics for suction curettage abortion: results of a clinical controlled trial," American Journal of Obstetrics and Gynecology,158(1):100-5 p 100, 1998
40. Sorenson et al, "A double-blind randomized study of the effect of erythromycin in preventing pelvic inflammatory disease after first trimester abortion," British Journal of Obstetrics and Gynaecology, 1992 May, 99(5):434-8
40a. "Women's Health After Abortion" by the De Veber Institute for Bioethics and Social Research, Toronto, Canada, 2002, p 66
41. Nielson et al, "No effect of a single dose of Olofaxcin on post-operative infection rate after first trimester abortion - A clinical controlled trial," Acta Obstetrica et Gynecologica Scandanavica, 1993 October, 72 (7):556-9
42. Barbacci et al, "Postabortal endometritis and isolation of chlamydia trachomatis," Obstetrics and Gynecology, 1986 November, 68(5):686-90
43. Sawaya et al, "Antibiotics at the time of induced abortion: the case for universal prophylaxis based on a meta-analysis," Obstetrics and Gynecology, 1996 May, 87 (5 pt 2): 884-90