Response to “The Enduring Association of a First Pregnancy Abortion with Subsequent Pregnancy Outcomes: A Longitudinal Cohort Study”

To the Editor,
In their recent publication, Studnicki et al1 examine the association between abortion of a first pregnancy and subsequent pregnancy outcomes among 5453 women receiving Medicaid benefits in seven United States. They conclude that women whose first pregnancy ends with abortion are more likely to end subsequent pregnancies with abortion, and that their health suffers as a result. Here we describe several methodological limitations that, in our view, introduce bias to the research and limit the conclusions that can be drawn from the results.
A key conclusion made by Studnicki et al1 is that “subsequent natural losses among women who had a first-pregnancy abortion were 1.53 times more common than among women whose first pregnancy ended in a live birth and 1.72 times more likely than women whose first pregnancy ended in a natural loss” (p. 3). However, the authors provide no evidence of testing the statistical significance of this difference between groups. The authors note that women who ended their first pregnancy with abortion recorded more pregnancies overall, but again do not assess the statistical significance of this difference or control for this when comparing on natural loss outcomes. These differences may be due to chance.