NRL News

Growing Evidence Linking Abortion to Subsequent Preterm Birth Being Ignored

by | Jun 13, 2012

By Randall K. O’Bannon, Ph.D., NRL-ETF Director of Education & Research

Byron C. Calhoun, MD

Most people understand that abortion is destructive of the child that a mother carries in her womb.  After all, that is the intention. But few people realize that there is scientific evidence that abortion often leads to the preterm birth of subsequent children, and in too many cases, a second dead child.

Byron C. Calhoun, MD, is a professor and vice chair of the Department of Obstetrics and Gynecology at West Virginian University in Charleston. Dr. Calhoun has researched, published, and presented more than a hundred scientific papers, 68 appearing in peer reviewed medical journals, many dealing with the topic of preterm birth and its causes.

In a briefing paper published April 28, 2012, by the International Organizations Research Group titled “Abortion and Preterm Birth: Why Medical Journals Aren’t Giving Us The Real Picture,” Calhoun presents both evidence of the link between abortion and subsequent preterm birth and the medical establishment’s unwillingness to acknowledge clear data and the danger.

Calhoun starts by noting the high incidence of preterm birth (any birth prior to 37 weeks gestation; anything after 37 weeks is considered full term, though pregnancy typically goes 40 weeks). Preterm births, Calhoun says, account for 6%-8% of all deliveries in Europe, Australia, and Canada, and 9%-12% of those in Asia, Africa, and the United States.  Preterm births are up by 15% since the 1980s, and the number of early preterm births (those before 32 weeks gestation) have increased by 5%.

What accounts for this increase?  Calhoun and his colleagues have looked at a number of factors observed in studies over the years and identified one element that shows up repeatedly in the data but is largely ignored in medical literature and official pronouncements–abortion.  In a 2007 analysis of 59 statistically significant studies which examined the factor, Calhoun found that induced abortion increased the incidence of subsequent preterm birth by approximately 31.5%.

Calhoun and his colleagues estimate the hospital costs alone associated with prematurity linked to this cause are more than $1.2 billion a year. This does not include any of the costs associated with the subsequent care connected to disabilities that often accompany premature birth such as cerebral palsy, deafness, vision, or breathing difficulties.

In this briefing paper, Calhoun notes new studies that buttress his team’s original claim.  A 2009 meta-analysis by H.M. Swingle and a team that included both pro-abortion and pro-life authors  looked at data from a dozen carefully selected studies from 1995-2007 that considered induced abortion as a factor found a 64% increased risk of early preterm birth from just one abortion.

Another team lead by P.S. Shah in 2009 looked at 18 studies on low birth weight and 22 studies on preterm birth, yielding a large number of patients.   Among the 280,529 patients having either no induced abortions or one abortion before their first completed pregnancy, Shah found an increased risk of preterm birth of 35% among the abortion patients. 

Among the five studies on low birth weight the Shah team looked at that considered multiple previous abortions, there was a 72% increase in preterm births for those with more than two abortions [1] demonstrating was Calhoun calls a “dose related effect.” This means that the more abortions a woman has before her first (completed) pregnancy, the higher the risk of a subsequent preterm birth.

A study by Gian Carlo Di Renzo, et al. from 2011 looked at birth data from nine different centers in Italy. Controlling for variables such as tobacco abuse, body mass index, previous cesarean section, as well as abortion, Di Renzo’s team found an increased risk of subsequent preterm birth of 95% with any previous abortion or abortions. (The study did not distinguish between those having one abortion or more; or distinguish those that may have followed other completed pregnancies.)

The major new study that is the focus of Calhoun’s briefing paper is a study by H. Liao et al in 2011. This examined four years of data from seven hospitals in Chendu, China which looked at delivery outcomes for more than 18,000 women.  Because of study design, researchers were able to compare data from women with no previous births who had surgical abortions, chemical abortions, or no abortions.

Calhoun reports that there was a 40% increase in preterm birth rates with one surgical abortion, a 62% increase with more than three surgical abortions, and a 218% increase among those having both previous chemical and surgical abortions.  Calhoun also noted that 20.3% of the chemical abortion patients needed post-abortion suction curettage to complete the abortion process and says that there was a 69% increased risk of preterm birth among women having chemical abortions at less than 7 weeks gestation and also having curettage.   Among that same group of patients, the risk of early preterm delivery (at less than 32 weeks gestation) was 360% greater.

Despite this data, Calhoun notes that the finding that Liao and colleagues chose to emphasize in their abstract was not the increased incidence of preterm births in the conditions above, but that “[a] history of multiple first trimester mifepristone-induced abortion is not associated with a higher risk of preterm delivery among singleton births in the first subsequent pregnancy.”

Calhoun says that just as Liao et al. ”buried the most important clinical and statistical findings” in their paper, “the link between preterm birth and abortion has been buried in medical literature.” To illlustrate further, Calhoun shares that though there are 127 peer reviewed studies demonstrating a statistically significant risk of preterm birth after abortion, a 2012 World Health Organization (WHO)  report continues to assert that “Very little is known about the causes and mechanisms of preterm birth, and without this knowledge, preterm birth will continue.”

That same WHO report finds that 15 million babies are born prematurely each year, that preterm birth rates are increasing in nearly every country with reliable data, and that prematurity is the leading cause of newborn deaths.   Calhoun reports that preterm births lead to some three million deaths a year worldwide.

Given the stakes, Calhoun says that continued efforts to deny the link between abortion and preterm birth are “dishonest, disingenuous, and disrespectful.” 

Women who turn to abortion to address their immediate “problem” need to know that they may also be risking the lives of any future children they might have.

[1] In seven of the 22 studies that looked exclusively at preterm birth and noted multiple previous abortions, the increased risk with more than two abortions was 93%.


Categories: Abortion