January 30, 2015 — A study has found that women who use Zoloft during pregnancy may be more likely to have a baby with a heart defect or a skull defect known as craniosynostosis.

The American Journal of Obstetrics & Gynecology published a study linking Zoloft with a 34% increased risk of atrial/ventricular septal defects (“hole in the heart”), and a 2.03-fold increased risk of craniosynostosis.

Craniosynostosis occurs when the soft bone plates on an infant’s skull harden prematurely, resulting in an abnormally-shaped, small head. In severe cases, babies need surgery to give the brain enough room to grow.

Overall, the use of Zoloft was not associated with an increased risk of birth defects when compared to non-use of antidepressants in pregnancy.

The conclusions of the study were based on data from nearly 18,500 pregnancies in Quebec, Canada from 1998-2010. The data included 366 pregnant women who used Zoloft, nearly 2,000 who used other SSRI antidepressants, and nearly 1,300 who used non-SSRI antidepressants.

This study is not the first to link Zoloft and heart defects or craniosynostosis.

One study published in the New England Journal of Medicine in 2007 found that Zoloft doubled the risk of septal heart defects, but did not increase the risk of craniosynostosis.

Another study, also published in the NEJM in 2007, found a 2.5-fold increased risk of craniosynostosis but no increased risk of heart defects associated with SSRI use during the first trimester of pregnancy.