Newborns of mothers who took a selective serotonin reuptake inhibitor (SSRI) in late pregnancy have an increased risk of persistent pulmonary hypertension, according to an article in the February 9 issue of the New England Journal of Medicine.

Persistent pulmonary hypertension is a serious condition that typically involves severe respiratory failure in a newborn infant and requires immediate treatment. The condition occurs in about 1 to 2 per 1000 babies.

Between 1998 and 2003, US investigators led by Christina Chambers, PhD, University of California at San Diego enrolled 377 women whose infants had the condition and 836 matched control women and their infants. Maternal interviews were conducted by nurses, who were blinded to the study hypothesis, regarding medication use in pregnancy and potential confounders, including demographic variables and health history.

Fourteen infants with persistent pulmonary hypertension had been exposed to a drug in the antidepressant class after completion of the 20th week of gestation compared with six control infants (adjusted odds ratio, 6.1; 95 percent confidence interval, 2.2 to 16.8). In contrast, neither the use a selective serotonin reuptake inhibitor before the 20th week of gestation nor the use of another antidepressant drug at any time during pregnancy was associated with an increased risk of the condition.

These findings may be important for pregnant women and clinicians when making decisions about the most appropriate treatments for depression late in pregnancy.

“Based on our findings, we estimate that 6 to 12 mothers per 1000 who use a selective serotonin reuptake inhibitor after 20 weeks’ gestation are likely to deliver a child with persistent pulmonary hypertension,” said Chambers. “Put in practical terms, the risk is relatively low -- about 99 percent of women exposed to one of these medications during the latter half of pregnancy will deliver an infant unaffected by [pulmonary hypertension].”

“Our findings suggest that prenatal exposure to selective serotonin reuptake inhibitors might contribute to the pathological origin of this disorder,” said Chambers. She added that although the study could not establish cause, several possible mechanisms suggesting an association between the use of the medications and the neonatal pulmonary condition are plausible.

Although the researchers noted an increased risk of PPHN in infants whose mothers took SSRIs late in pregnancy, the research team points out that mothers may need to continue SSRI treatment during pregnancy in order to care for themselves appropriately. The findings of this study might be factored into decisions about continuing treatment with SSRIs into late pregnancy.