Another Potential Effect of Maternal SSRI Use on Newborns

Why you may want to obtain ECGs in exposed infants.

In the newborn nursery, pediatricians commonly encounter infants born to mothers who were receiving selective serotonin reuptake inhibitors (SSRIs) for depression during pregnancy. Earlier studies suggested a number of potential effects of maternal SSRI use on the newborn; these included jitteriness, agitation, diarrhea, hypoglycemia, vomiting, hypothermia, respiratory distress, seizures, feeding difficulties, increased or decreased tone, low birth weight, and small size for gestational age.¹ In the past few years, studies have begun to focus on potential cardiac effects in exposed newborns; the latter include pulmonary hypertension and cardiovascular anomalies.

In adults, overdoses of SSRIs have been associated with QT prolongation. In a recent study published in Pediatrics, Dubnov-Raz and colleagues² investigated a possible relationship between maternal SSRI use during pregnancy and prolongation of the QTc interval in the newborn. The authors collected data from neonates born between January 2000 and December 2005 to mothers who were receiving SSRIs at the onset of labor. They excluded infants who were born before 35 weeks' gestation, who had an Apgar score of less than 7, who had an echocardiogram-identified cardiac lesion, or whose mothers took any other long-term medication during pregnancy or had hypothyroidism or gestational diabetes.

The investigators compared these infants with healthy neonates born during the same period who had had an ECG for evaluation of a murmur and whose mothers had not taken any long-term medications during pregnancy. Infants with identified cardiac abnormalities on echocardiogram were excluded from the control group. The 52 newborns who had been exposed to SSRIs in utero were matched by gestational age with unexposed infants to control for the effect of fetal age on ECG intervals. A single blinded pediatric cardiologist interpreted all the ECGs.

The mean QTc interval in the infants exposed to SSRIs was significantly longer than that in the unexposed infants, and results were similar no matter which SSRIs the infants' mothers had been receiving. The authors did not find an association between QTc interval and birth weight, and there were no electrolyte abnormalities in the affected infants.

Of the exposed newborns, 10% were found to have a pathologically prolonged QTc interval. Although the affected infants in the study did not experience any clinical cardiac events, and although their QTc intervals normalized once they were no longer exposed to the drug, it is possible that a temporary QTc prolongation could result in a clinical event.

The Dubnov-Raz study is limited by its small size. It is clear that additional studies need to be done to continue to evaluate the safety of SSRIs in pregnancy, not only with respect to reported neonatal problems and birth defects but also with regard to these agents' effect on QTc intervals.

Nonetheless, this study should alert us to a potential problem that could have significant consequences for the infants we care for. Because a prolonged QTc interval puts an infant at risk for cardiac events-and even sudden cardiac death-its identification could be lifesaving. Until the effects of SSRIs are investigated further, we, as primary care providers, should consider obtaining ECGs in infants born to mothers who are receiving these drugs at the time of delivery.