CHICAGO - Babies exposed to an antidepressant or a mood disorder during fetal life did not have any more signs of irritability, difficulty feeding, sleep disturbances and respiratory problems two to four weeks after birth than babies who were not exposed. Instead, the major factor associated with newborn problems was preterm birth, according to a new Northwestern Medicine study.

Similar studies have assessed babies earlier – less than two weeks – but this study looked at babies two to four weeks after birth. The additional time led the scientists to determine preterm birth as the main cause of these neonatal signs of agitation, excessive crying, rigidity, tremors and restlessness, typically called Neonatal Discontinuation Syndrome (NDS).

Preterm birth was the primary contributor to babies’ irritability, difficulty sleeping and more

Many women are concerned about taking antidepressants because they’ve heard the presence of these neonatal signs are more common in babies exposed to antidepressants.

“I believe that is true directly after birth, but this study shows those signs appear to be short-lived,” said senior author Dr. Katherine Wisner, the Norman and Helen Asher Professor of Psychiatry and Behavioral Sciences and Obstetrics and Gynecology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine psychiatrist. “At two to four weeks postpartum, the signs women were reporting to us were more associated with preterm birth rather than whether their babies were exposed.”

The additional two weeks also gave parents time to adjust to their newborns at home to better assess if their infants’ behaviors were of concern to them. They could look for signs that couldn’t be readily assessed during typical, 10- to 15-minute doctor examinations, such as length of sleep post-feeding, fever, projectile vomiting and stool characteristics.

The study was published May 24 in the Journal of Clinical Psychiatry.

“Most pregnant women are naturally going to worry more about their baby’s health than their own and might forego taking an antidepressant to avoid these neonatal signs,” said first author Amy Yang. “But with the information from this study, they can be reassured that the baby’s behavior at two to four weeks after birth is not likely due to exposure to medication or depression.

The researchers studied 214 mothers who were divided into three groups: Women with a mood disorder who were not taking any antidepressants; women with a mood disorder who were taking a serotonin reuptake inhibitor (SRI) antidepressant; women who did not have a mood disorder and were not taking an SRI antidepressant (comparison group).

They evaluated the babies for signs on the Finnegan Scale, which lists 21 symptoms that are most frequently observed in infants who have been exposed to illicit or prescription drugs. The rates of sign presence in the SRI, mood disorder and comparison groups were similar at 34.1 percent, 35.1 percent and 30.4 percent, respectively.

“We observed a significant relationship between Finnegan signs and preterm birth independent of SRI antidepressant exposure,” said Yang, biostatistician for Northwestern’s Asher Center for the Study and Treatment of Depressive Disorders. “Studies of NDS should consider the contribution of preterm birth to infant behavior.”

This work was supported by National Institute of Mental Health grants R01 MH-60335 and R01-MH07592.