AF Risk Increases with More Pregnancies?

FEBRUARY 12, 2017

Two recently-published studies examine how pregnancies may affect a woman's heart health later in life.

One study linked multiple pregnancies to an increased risk of developing atrial fibrillation later in life, and another investigated the association between premature delivery and cardiovascular disease.

In this first analysis to investigate a link between number of pregnancies and atrial fibrillation, researchers led by Jorge A. Wong, MD, MPH, at McMaster University in Hamilton, Ontario, Canada, and Christine M. Albert, MD, MPH, at Brigham and Women’s Hospital in Boston, analyzed data from 34,639 participants from the Women’s Health Study.  Study participants were a median age of 53, had a median of two prior pregnancies and were healthy at the start of the study. They completed annual questionnaires and observational follow-ups. After an average 20 years of follow up, 1,532 atrial fibrillation cases had occurred.

“We found that an increase in the number of pregnancies was associated with a higher risk of future atrial fibrillation,” Wong said. “For example, women with four or more pregnancies were approximately 30% to 50% more likely to develop atrial fibrillation compared to women with no pregnancies.”

Researchers speculate that the repeated exposure to physiological, metabolic or hormonal factors during pregnancy could explain the link.

“The point here is not to discourage women from having children,” Wong said in a press release about the study. “However, our research highlights that something about pregnancy predisposes women to this greater risk, and more research is needed to help us understand why.”

In a separate study, researchers led by Lauren Tanz, MSPH, at the Harvard T.H. Chan School of Public Health and Janet W. Rich-Edwards, Sc.D., at Brigham and Women’s Hospital, both in Boston, investigated the association between having delivered a premature baby and cardiovascular disease.

Researchers reviewed data on 70,182 women in the Nurses’ Health Study II and found that women who deliver a premature baby before 37 weeks gestation in their first birth have a 40% greater risk of later cardiovascular disease compared to women who delivered at term, and those who deliver before 32 weeks are at twice the risk compared to full-term deliveries.

“Preterm delivery is independently predictive of cardiovascular disease, even after adjustment for multiple cardio-metabolic risk factors, and the association is only partially mediated by the postpartum development of traditional cardiovascular risk factors,” the authors wrote. “Ultimately, preterm delivery may be a useful prognostic tool to identify high-risk women early in life who would benefit from early screening, prevention, and treatment.”

Wong JA, Rexrode KM, Sadhu RK, Conen D, Albert CM. Number of Pregnancies and Atrial Fibrillation Risk: The Women’s Health Study. Circulation. 2017;135:622-624.

Tanz LJ, Stuart JJ, Williams PL, et a.  . Circulation. 2017;135:578-589.