Pregnant women who use certain popular antidepressants may have a twofold increased risk for delivering babies with a rare but serious lung disorder, a new study finds.Researchers analyzed national registry data from 1.6 million births in five Nordic countries in an effort to determine if using selective serotonin reuptake inhibitor (SSRI) antidepressants during pregnancy raises the risk for neonatal pulmonary hypertension, a life-threatening condition in newborns that normally occurs in one to two births in 1,000.
SSRIs such as Celexa, Lexapro, Paxil, Prozac, and Zoloft are the most widely prescribed class of antidepressants, and millions of women in the U.S. have used them during pregnancy.
Persistent pulmonary hypertension in newborns (PPHN) is a respiratory disorder in which the arteries leading to the lungs remain constricted after birth, limiting blood flow and oxygen.
Risk factors for PPHN include maternal obesity, diabetes, and smoking, and between 5% and 10% babies with the disorder do not survive.
A 2006 study first linked SSRI use during pregnancy to the disorder, finding a sixfold increase in the incidence of neonatal pulmonary hypertension in babies exposed to the antidepressants in the last months before birth.
Studies conducted since then have been mixed, with some supporting the association and others finding no increase in risk associated with SSRI use.
In the newly published study, researchers from Stockholm, Sweden’s, Karolinska Institute examined birth registry data from all babies born between 1996 and 2007 in Denmark, Finland, Iceland, Norway, and Sweden.
About 30,000 women used SSRIs during pregnancy, and about 11,000 filled prescriptions for them in their fifth month of pregnancy or later.
There were 33 cases of persistent pulmonary hypertension among babies whose mothers took SSRIs late in pregnancy, or about three cases per 1,000 births.
This was about double the number of cases that would have been expected in the general population of newborns, but babies born to mothers with a history of a previous hospitalization for a psychiatric disorder who were not taking SSRIs during pregnancy also had a slightly increased risk for the disorder.
Gideon Koren, MD, of Toronto’s Hospital for Sick Children, says the study raises more questions than it answers.
“This is by far the largest study to examine SSRI use and PPHN, but the fact that women with untreated depression had a higher risk for the disorder raises new doubts about this link,” Koren says. “Many doubts remain, and they should be shared with patients.”
Koren directs the Toronto hospital’s “Motherisk” program, which advises women about drug safety during pregnancy.
“We talk to about 200 women a day from all over North America and other parts of the world,” he says, adding that questions about SSRI safety are common.