Infants whose mothers used selective serotonin reuptake inhibitors during late pregnancy are at increased risk for drug-related adverse neurologic effects during the first weeks of life, according to an article in the July issue of the Archives of General Psychiatry.

According to the article, the class of agents is commonly used as treatment for mood or anxiety disorders in pregnant women. Previous studies had suggested that use of the drugs during the third trimester can lead to neurologic symptoms in newborns including irritability, constant crying, eating and sleeping difficulties, and even generalized seizures.

In the current study, Kari Laine, M.D., Ph.D., and her Finnish colleagues evaluated the effects of selective serotonin reuptake inhibitors on newborns exposed to the drugs during the third trimester of pregnancy. The researchers enrolled 40 pregnant women in their study between January 1, 1997 and August 31, 2000. Of the total, 20 women used a reuptake inhibitor during pregnancy and breastfeeding. The other 20 women did not use any psychoactive medication.

The newborns were assessed for serotonin-related neurologic symptoms including muscle spasms, restlessness, tremor, shivering, rigidity and poor coordination on the first 4 days of life and again at 2 weeks and 2 months after delivery. Infants also underwent brain ultrasound and magnetic resonance imaging at 38 to 42 weeks after conception and again at the age of 2 months.

The researchers found there were no major differences in basic vital signs (blood pressure, heart rate, body temperature) in the 2 groups of infants during the first 2 months of life. There was a significant 4-fold difference in serotonin-related symptoms during the first 4 days of life between the infants of the 2 groups. The most common symptoms in newborns exposed to medication included tremor, restlessness, and rigidity. The researchers also found a significant reduction in serotonin-related symptoms from 1 to 4 days to 2 weeks in the drug-exposed group, with no significant difference in symptoms detectable between the groups of infants at 2 weeks of age.

"In conclusion, we report increased risk for central nervous system serotonergic adverse effects during the first days of life in newborns of mothers taking the selective serotonin reuptake inhibitors citalopram or fluoxetine during the third trimester of pregnancy," wrote the authors.

"The clinical relevance of the present results is awareness of the psychiatrists who prescribe selective serotonin reuptake inhibitors during pregnancy and the pediatricians who treat the serotonin-related neurologic symptoms of the newborns during the first days of life," the researchers write. "Although these effects seem to subside quickly, they may expose the infants to more serious neonatal complications such as convulsions."