Dr. Martin McCaffrey on the Abortion-Preterm Birth Link


We are continuing our review of the presentations given at 2017 Convention in April. You may also find these presentations in our quarterly member publication, MCFL News.

Dr. Martin McCaffrey, neonatologist at the University of North Carolina School of Medicine and star of the documentary Hush, hit a nerve all too familiar to a pro-life audience as he began his presentation on the current crisis of preterm birth. McCaffrey noted that information that conflicts with the culture’s pro-abortion agenda will be hidden from public view. “You are not going to hear this information anywhere else until it gets published mainstream. I’m not sure when that’s going to happen,” he said.

McCaffrey, who served as a neonatologist in the for Navy 26 years, promised the Convention audience a whirlwind tour. “I have a real interest in the topic of abortion and preterm birth. My goal in life is to put myself out of business. My business is preterm babies and unfortunately I don’t see myself going home any time soon.”

In 2015, 9.6% of all babies born in US were preterm, a percentage that has risen 20% in the last 20 years. Premature birth (PTB) is defined as birth prior to 37 weeks and differs from low birth weight. Low birth weight is defined as birth weight less than 2500 grams or 5 pounds.

Another category of preterm birth is very preterm birth (VPB), babies born at less than 32 weeks. In 2015, 63,000 US births were very preterm births. These constitute 1.6% of all births and are associated with the highest risk for death and morbidity: respiratory distress, brain bleeding, blindness, hearing loss, mental retardation, and cerebral palsy. The annual cost of care for very preterm babies, just for their first year of life, is $26 billion.

McCaffrey referred to a 2006 report by the Institute of Medicine of the National Academy of Science: ‘Preterm Birth: Causes, Consequences, and Prevention.’ “Note the table listing ‘immutable’ risk factors associated with preterm birth,” he said. “’Immutable’ can mean that we don’t have a way to deal with these factors medically, or can mean that something has happened that we can never change and will impact future pregnancies forever. Buried in the report, on page 625 as an immutable risk factor, is prior first term induced abortion. How many have ever heard that abortion is a risk factor for preterm birth? How many have heard it from a professional organization such as the American Congress of Obstetricians and Gynecologists, the American Academy of Pediatrics, or the Centers for Disease Control (CDC)?” McCaffrey asked.

“Much is made of ‘mutable’ risk factors such as cigarette smoking, the use of alcohol or illegal drugs, and the lack of prenatal care as ways of reducing preterm birth. But what is the actual evidence that it really leads to problems with babies, specifically preterm birth?” he questioned. McCaffrey said that mainstream science accepts research associating smoking with preterm birth while denying the much stronger evidence associating abortion and PTB.

In 1964, the Report of the Advisory Committee to the Surgeon General noted studies showing an association between maternal smoking, lower birth weight, and a significantly greater number of premature deliveries (defined as birth weight of 2,500 grams or less) than non-smoking controls. 

“As I said before, birth weight and gestational age are two very different things,” he explained. “There is good evidence for the association with smoking and smaller size babies, but it does not mean that smoking is a risk factor for premature delivery.

“In 1984, a systematic review meta-analysis of previous studies found a mixed bag of results, estimating that maternal smoking raised the risk of PTB by 27%,” McCaffrey said. “What is amazing is the meta-analysis admitted ‘publication bias may affect the results of this study but we believe its contribution is minimal.’ No one who is studying abortion and preterm birth could make that statement and get their report published.”

The data associating abortion and preterm birth is impressive. 145 statistically significant studies, dating from 1963 to the present, demonstrate the association of preterm birth and abortion. Twenty-six statistically significant studies demonstrate the association of very preterm birth or very low birth weight (less than 1500 grams) with abortion. Any large study, with at least 30,000 mothers or 500 deliveries less than 33 weeks, shows an association of abortion and preterm birth.

 McCaffrey examined findings from a 2009 meta-analysis by Swingle, et al, showing that one induced abortion increased the risk of preterm birth by 25%. More than one induced abortion increased the risk of preterm birth, a dose response effect, by 50% and multiple abortions were associated with an increased risk of very preterm birth by 64%.

He also looked a study by Hardy et al, on the effect of abortion on early preterm births. The study found a 45% increased risk for a baby born at 32 weeks, a 71% increased risk for a baby born at 28 weeks, and a 117% increased risk for a baby born at 26 weeks. “That’s important when we are looking at a 26 week baby who is very different from a 32 week baby. The chances for survival are very different, complications are very different, how you talk to parents and families is very different,” McCaffrey explained.

A Finnish study from 2012, Klemetti, et al, found increased odds for very preterm births that also exhibited a dose–response relationship: 19% for one abortion, 69% for two abortions, and 178% for three abortions. The study recommended that “Health education contain information of the potential health hazards of repeat induced abortions, including very preterm birth and low birth weight in subsequent pregnancies.”

The Finnish study also noted, “Observational studies like ours, however large and well-controlled, will not prove causality.” McCaffrey was incredulous, asking, “Did we ever prove causality for smoking?” But with abortion we have to prove causality, not just association.”

“You have to realize all this data is out there,” he repeated citing yet another study, Lemmers et al. from 2016 that said “The meta-analysis shows that women with a history of a dilatation and curettage (D&C) procedure for either termination of pregnancy or completion of miscarriage is associated with an increased risk of subsequent preterm birth. The increased risk in association with multiple D&Cs indicates a causal relationship and warrants caution in the use of surgical uterine evacuation.”

McCaffrey examined the issue of whether medical abortion might pose less risk of preterm birth than surgical abortion. Virk J et al.: ‘Medical abortion and the risk of subsequent adverse pregnancy outcomes’ was published by the NEJM 2007. “It’s a landmark study that said medical abortion had the same risk for PTB instead of surgical abortion. This was a well-done study with a big flaw. There was no control group of women who never had an abortion so the researchers assumed that surgical abortion posed no risk for PTB.

“If medical abortion poses the same risks as surgical abortion, as we’ve seen from the previous evidence, then you could conclude that medical abortion is problematic,” McCaffrey. “However, I think the jury is still out on whether medical abortion is safer as far as impact on preterm birth.”

Oliver-Williams et al: ‘Changes in Association between Previous Therapeutic Abortion and Preterm Birth in Scotland, 1980-2008,’ saw a decreased risk for preterm birth as practice changed in favor of medical abortions. “What is landmark about these studies are the comments,” McCaffrey said. “People are either not reading them, or it is so ingrained in how they think about abortion that there’s nothing unusual about them. Quoting from the study McCaffrey read, “We speculate that changes in the methods used to achieve termination of pregnancy are the most plausible explanation for the loss of the association between previous abortion and the subsequent risk of preterm birth…The above interpretation assumes a causal association between surgical abortion without cervical pre-treatment and preterm birth, and there are a number of aspects of the current analysis that are supportive of a causal relation.”

“So, is medical abortion without risk for future preterm birth?” McCaffrey asked. “While admitting that surgical abortion increases the risk for preterm birth, some proponents of medical abortion advance the theory that injury from surgical abortion is the reason abortion has increased preterm birth risk. But we don’t know for sure, other things could be going on. This is an assumption not supported by current research.”

McCaffrey said it is still unknown exactly how abortion causes preterm birth. Potential causes include: cervical trauma and injury, induction of or predisposition to inflammation, maternal stress, and other unknown factors. Referring to medical abortion McCaffrey said, “The sudden loss of progesterone function upon mifepristone administration differs from the more gradual withdrawal of progesterone that occurs during a normal term birth. It’s not natural and a lot of unusual things can happen. We just don’t have the science.”

In 1965, Bradford Hill noted nine conditions that help strengthen causal inference for an observed association: strength of the association, consistency, specificity, temporality, dose response, plausibility, coherence, experiment, and analogy. These were used to establish the link between cigarette smoking and lung cancer. “Hill said his viewpoints aren’t indisputable evidence, but what they can do is to help us make up our minds on the fundamental question – is there any other way of explaining the facts before us? All scientific work is incomplete, is likely to be upset or modified by advancing knowledge. That does not confer a freedom to ignore the knowledge we already have, or to postpone an action that it appears to demand at a given time,” McCaffrey said.

“Is anybody listening?” McCaffrey wondered. “It takes courage for researchers to speak out. Dr. Phil Steer, editor of the prestigious British Journal of OB/GYNs wrote, ‘We have known for a long time that repeated terminations predispose to early delivery in a subsequent pregnancy.’ Really? Who’s been told that? The American Congress of OB/GYNs (ACOG) has never said that. This is buried in his editorial. This is astounding.”

“ACOG has ignored the Hill criteria claiming there is no risk from abortion to future pregnancies. ACOG protects the interests of OB/GYNs, not the interests of the patients,” McCaffrey said. “Until ACOG is willing to say something, even if OB/GYNs recognize the truth, they are not going to say anything. This is problematic.”

McCaffrey is not immune from mainstream prejudice. In 2014, he submitted an article, “The Abortion-Preterm Birth Association,” to the American Academy of Pediatrics asking that they incorporate counseling for adolescents on the risk of preterm birth after an abortion in their health guidelines pathway. “The comments on my manuscript didn’t review the science of the article,” he said. “One comment read ‘The recommendation to let the teen know about a possible association of abortion and a future preterm birth has a strong flavor of a ‘right to life’ message that is not relevant to or supportive of a teen’s decision making.’ This is astounding. The mindset of academia is not academic. It’s protecting a political policy position.”

McCaffrey estimated the impact of abortion on very preterm birth using 2010 statistics. “Twenty-two percent of VPB is attributable to abortion, or 14,212 a year. Of these the mortality rate for infants less than 32 weeks was 17%, making 2,373 deaths attributable to abortion. The cost caused by abortion since 1973: 625,328 VPBs attributable to abortion, the population of Baltimore. 102,309 deaths, the same number of deaths caused by the atomic bomb on Hiroshima. Just the initial neonatal intensive care amounts to over a billion dollars a year.

“We need to create informed consent and inform the public of the impact of abortion on preterm birth,” Mccaffrey said. “The CDC doesn’t mention it. The March of Dimes doesn’t say anything.”