Abortion Linked to Subsequent Premature Births

By Randall K. O'Bannon, Ph.D.

Women who are informed know of abortion's link to breast cancer, to infertility, and to future ectopic pregnancy. Now there is strong evidence that an abortion substantially increases the likelihood of subsequent premature births.

"Induced Abortion and Risk of Later Premature Births" appears in the Summer 2003 edition of the Journal of American Physicians and Surgeons. The study, authored by Brent Rooney and Byron Calhoun, M.D., points out that at least 49 studies conducted between 1966 and March 2003 have shown a statistically significant increase in premature births or "surrogates" such as low birth weights in women who have had prior induced abortions.

In 36 years of studies tracked by Rooney and Calhoun, only eight studies failed to show a statistically significant increase, and in many cases this was simply because the sample sizes were too small. There were no studies found in recognized medical journals during this period showing a decreased risk of subsequent prematurity following an abortion.

The report offered some astounding results. A 1993 Australian study of 121,305 total births found the risk of an extremely premature birth (20-27 weeks gestational age) to be 60% higher for women with one previous abortion, 150% higher for those with two abortions, and 460% higher for women having three or more previous induced abortions - - compared to women with no previous pregnancies.

The researcher doing the Australian study also found the risk of prematurity following an abortion higher than the risk associated with other factors that have sometimes been connected with prematurity, such as maternal age, number of previous pregnancies, marital status, and socioeconomic status. She also noted that each preterm birth increased the likelihood of subsequent preterm births, while each full-term birth diminished the risk.

Notably, most of the abortions involved were vacuum aspirations rather than dilation and curettage, a strong indicator that the risk was more than simply a matter of more aggressive surgical intervention.

These 1993 results were confirmed in 1998 by the same researcher in a follow-up study that involved twice as many Australian births. Besides validating earlier results, the researcher found women with four or more abortions had nine times the risk of extremely premature births as women with no prior pregnancies.

A 1994 German study tracking 106,345 births in Bavaria showed similar results. A woman having one previous abortion had two and a half times the risk of having a subsequent premature birth. (In this study, this was considered as any birth at less than 32 weeks gestation.) The risk was 5.2 times higher for a woman with two previous abortions and eight times higher for a woman with three or more previous abortions.

The idea that results may be skewed by "recall bias" is challenged by a 1999 study of women from Denmark, which has long compiled a national abortion registry. (As the authors describe it, recall bias is "the hypothesis that women with prior IA [induced abortions] who deliver prematurely are more accurate in reporting reproductive history than women who deliver at full term.") This study of 61,753 women found that an induced abortion nearly doubled a woman's risk of a subsequent premature birth - - here, considered as any birth less than 34 weeks.

Women aborted by vacuum aspiration were 1.82, 2.45, and 2.00 times more likely to give birth before 37 weeks in following pregnancies if they had one, two, or three or more previous abortions, respectively. The odds of a subsequent premature birth (less than 37 weeks) for women aborted by dilation and evacuation were 2.27 times higher for one previous abortion. That figure rose to 12.55 times higher for women having two previous dilation and evacuation abortions.

Given what is known about both abortion and premature birth, Rooney and Calhoun find the association plausible. For example, one of the known risks of surgical abortion is the possible development of an incompetent cervix (a cervix that has difficulty remaining closed during pregnancy). For obvious reasons, this itself is a risk factor for premature birth.

Women who delay their first full-term pregnancy until they are older than 35 by having multiple abortions add their abortion-generated risk to the general risk of prematurity that comes for all women giving birth for the first time after age 35. Infections, uterine adhesions, and the mental distresses that accompany abortion are also risk factors for later premature births.

These findings have serious medical, economic, and legal implications. Some 6% of all births are preterm, translating to about 180-240,000 of the 3-4 million births in the U.S. each year.

About 30,000-40,000 births a year are very preterm, occuring at less than 28 weeks gestation. According to Rooney and Calhoun, low birth weight and premature birth are the most important risk factors associated with infant mortality or later disability, as well as lower

cognitive ability and later behavioral problems. The costs associated with the treatment and care of such children, both at birth and as they age, can be tremendous, and parents often sue to recover some of these costs if they suspect negligence on the part of the doctor.

Abortionists who fail to adequately warn patients of such future risks, say Rooney and Calhoun, may thus be liable for substantial damages.

Rooney and Calhoun point out that the median damage award in the U.S. for medical negligence in attending at childbirth between 1994 and 2000 was just over $2 million. Rooney and Calhoun conclude that abortionists who merely point out the risk of infection or an incompetent cervix as potential abortion complications, without informing women how these may lead to future prematurity and its sequelae, may not escape liability.

Owing to increasing evidence that abortion not only destroys the baby, but physically and emotionally damages women, pro-lifers have made the point that every abortion has at least two victims. This latest evidence shows there often may be more than two, as that circle of harm extends to a woman's future offspring.

Dr. O'Bannon is NRL-ETF director of education and research.