According to a new study published in the American Journal of Obstetrics & Gynecology, among a sampling of 3,000 pregnant women who started SSRI antidepressants during the second or third trimester were found to be 5 times more likely to have a preterm delivery. The researchers also found a higher risk of preterm delivery among women who  . . .

 . . . took anti-anxiety drugs known as benzodiazepines, regardless of when they began treatment. Those drugs, which include medications like lorazepam (Ativan) and alprazolam (Xanax), were linked to higher risks of other complications as well - including low birth weight, newborn respiratory distress and a low Apgar score, a standard measure of newborn health.

The study included 2,793 pregnant women, 11 percent of whom used a psychiatric medication during pregnancy. Of these, 138 were on an SSRI, while 85 used a benzodiazepine. Among women who were not on any medication, 9 percent gave birth prematurely, versus nearly half of women on benzodiazepines. Meanwhile, 14 percent of women on SSRIs had a preterm birth, but the elevated risk turned out to be concentrated among those who started an antidepressant after the first trimester. Of those 21 women, 16 delivered prematurely. Several other birth complications, often related to preterm birth, were also higher-than-average among women on benzodiazepines. Seventeen percent of their newborns suffered respiratory distress syndrome and one-third ended up in the neonatal intensive care unit. Those figures were 3 percent and 6 percent, respectively, among newborns whose mothers had not used psychiatric medications during pregnancy. Calderon-Margalit pointed out that most women on benzodiazepines used lorazepam (Ativan), so it is possible that the risks are associated mainly with that drug. However, further research is needed to determine whether any particular medications carry particular risks.

SOURCE: American Journal of Obstetrics & Gynecology, December 2009.