U/S study shows impact of prenatal SSRIs, maternal depression

• Maternal SSRI use associated with smaller fetal head size and increased risk of preterm birth

• Untreated maternal depression associated with smaller fetal head and body size but not increased risk of preterm birth

Use of selective serotonin reuptake inhibitors (SSRIs) during pregnancy is associated with smaller fetal head circumference-a prenatal marker of brain volume-and with a higher risk of preterm birth (< 37 weeks), according to findings from a prospective population-based study from the Netherlands.

Untreated maternal depression, on the other hand, is associated with slower rates of fetal body and head growth, although the impact was less on head growth than with SSRIs.

Published in the Archives of General Psychiatry, the study included 7,696 pregnant women. Of them, 7,027 had no or low-level depressive symptoms, 570 had depressive symptoms but did not use SSRIs, and 99 used SSRIs, as determined via self-report and pharmacy records.

Repeat ultrasonographic measurements of the fetuses of women with depressive symptoms showed smaller bodies and heads but no increased risk of preterm birth. In contrast, fetuses born to women who used SSRIs prenatally had smaller heads, but not bodies, and double the risk of preterm birth.

The authors theorize that smaller heads in fetuses whose mothers took SSRIs could be a result of residual depressive symptoms, past depression affecting fetal development, SSRI impact on fetal serotonin and  brain growth. Factors that accompany depression or use of SSRIs, such as smoking or drinking during pregnancy or low socioeconomic status, also may be at work, although the latter is less likely to explain the specific effect on head size.

The investigators believe the study is important because few data exist regarding the safety of SSRIs in pregnancy. The findings, however, raise a question about whether drug therapy during pregnancy is better or worse for the fetus than no treatment.

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