Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed antidepressant drugs, but whether or not they’re safe for women with mental illness to take during their pregnancy has long been up for debate. Some studies have shown taking SSRIs during pregnancy can increase risk for birth defects, while others have suggested antidepressants may not risk newborns' health after all. In the newest study published in The American Journal of Psychiatry, researchers conclude it really depends.

This particular study sources its data from national registries in Finland, where up to 10 percent of women are prescribed SSRIs, researchers cited. The risks SSRIs pose to a woman’s pregnancy (though the drugs are considered relatively safe) include preterm birth, being born small for gestational age, and postpartum hemorrhage. At the same time, 10 percent of pregnant women report depressive disorders — and depression alone has been associated with negative pregnancy outcomes.

To better understand these possible links, researchers looked at 845,345 women and their newborns, dividing each woman into one of three groups: women taking SSRIs; women not taking any medication for their mental illness; and women who had been exposed to SSRIs without a diagnosed mental illness. Additionally, researchers sourced data on women’s prescription drug purchases, their psychiatric history, and the hospitals they visited.

The results showed women taking SSRIs during pregnancy were at lower risk for late preterm (32-36 gestational weeks) and very preterm birth (less than 32 weeks) compared to the group of women not taking SSRIs for their mental illness. Women taking SSRIs were also at lower risk for Caesarean section (C-section). However, researchers did find SSRIs also cause neonatal problems.

“SSRI use was associated with an increased risk of all neonatal problems, including hospital stay at seven days age,” researchers wrote. “Maternal psychiatric disorder without antidepressant use was associated with an increased risk for late preterm and very preterm birth, need for monitoring, and hospital stay at eight days age as compared to [women exposed to SSRIs without being diagnosed with mental illness].”

Senior study author Dr. Alan Brown, a professor of psychiatry and epidemiology, explained in a press release these “novel findings” suggest that previous research on the effects antidepressants has on pregnancy holds up: They are, largely, associated with a lower risk of preterm birth and C-section, but also a higher risk for several neonatal problems.

In which case, Brown concludes taking SSRIs during pregnancy “should be an individualized approach” based on both the mother’s medical and psychiatric history.

Source: Brown A, et al. Pregnancy complications following prenatal exposure to SSRIs or maternal psychiatric disorder – results from population-based national register data. The American Journal of Psychiatry. 2015.