Taking a popular type of antidepressant during pregnancy may increase the risk for preterm birth, the need for treatment in a neonatal intensive care unit and lower overall health for the baby, according to a new study.

Researchers compared birth outcomes among babies born to 329 women who took selective serotonin reuptake inhibitors (SSRIs) during pregnancy, 4,902 women who had a history of psychiatric illness but did not take SSRIs during pregnancy and 51,770 women with no history of mental illness.

Compared with women who had no history of mental illness, those who took SSRIs during pregnancy gave birth an average of five days earlier and had double the risk for preterm delivery. Babies of mothers who took SSRIs during pregnancy were significantly more likely than infants in the other two groups to have a five-minute Apgar score of seven or lower (seven is the general indicator of good infant health) or to be admitted to the neonatal intensive care unit. Exposure to SSRIs did not affect birth weight or head circumference.

The researchers also found that SSRI-exposed infants admitted to the neonatal intensive care unit had symptoms including seizures, jitteriness, infections, respiratory problems and jaundice that may have been caused by withdrawal from SSRIs or adverse effects from them.

The findings appear in the October issue of Archives of Pediatrics & Adolescent Medicine.

The study justifies increased awareness to the possible effects of intrauterine exposure to antidepressants, the researchers concluded. However, treatment of depression during pregnancy may be warranted, and future studies need to distinguish between individual SSRIs to find the safest medication.

It's estimated that more than 10 percent of pregnant women have depression. The authors noted that SSRIs have been shown to cross the placenta and be present in the umbilical cord blood of infants whose mothers took the drugs during pregnancy.