NEW YORK (Reuters Health) - Pregnant women who take certain drugs for depression or anxiety may have heightened risks of preterm delivery or other birth complications, according to a new study.
Researchers found that among nearly 3,000 women who gave birth in Washington State, those who started taking antidepressants known as selective serotonin reuptake inhibitors (SSRIs) in the second or third trimester had a higher risk of preterm birth.
Compared with their counterparts not on the medications, these women were nearly five times more likely to deliver prematurely.
The same risk was not seen, however, among women who started on an SSRI before pregnancy or during the first trimester. SSRIs include drugs like sertraline (Zoloft), paroxetine (Paxil) and fluoxetine (Prozac).
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 findings of the study are published in the American Journal of Obstetrics & Gynecology.
Exactly what the study means for women on SSRIs or benzodiazepines is not entirely clear. A major limitation is that it could not estimate the benefits of treatment, lead researcher Dr. Ronit Calderon-Margalit, of the Hebrew University-Hadassah School of Public Health in Jerusalem, noted in an email to Reuters Health.
Any risks of using the medications during pregnancy need to be balanced against the risks of leaving depression and anxiety disorders untreated.
“It is very important to have other studies of the risks associated with (these) drugs, but also of benefits associated with treating mothers,” said Calderon-Margalit, who was at the University of Washington in Seattle at the time of the study.
In addition, SSRIs did not appear to present equal risks for all women. Calderon-Margalit described the antidepressant findings as “mostly reassuring” for women who start the drugs before pregnancy or in the first trimester — as most SSRI users in the study had.
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.