WASHINGTON — Even though the sleeping aid zolpidem crosses the placenta, use of the drug during pregnancy does not appear to significantly affect outcomes, a study of 45 women shows.
The study, presented as a poster at the annual meeting of the American Psychiatric Association, included pregnant women who were enrolled in a prospective study of the pharmacokinetics of psychotropic drugs during pregnancy and who were treated with zolpidem (Ambien) during pregnancy. Maternal diagnoses were determined using the Structured Clinical Interview for DSM-IV (SCID). Maternal and cord blood were obtained at delivery when possible.
The placental passage rate was calculated as the ratio of medication concentration in the umbilical cord plasma to that in maternal plasma. When umbilical cord concentrations were below the limit of detection (less than 4.0 ng/mL), this value was used for data analysis. This approach was thought to be conservative, erring toward overestimation of fetal exposure to zolpidem. When both maternal and umbilical plasma concentrations were less than the detection limit, the pair was excluded from the analysis.
Obstetrical and neonatal outcomes in women who had given birth to a live infant after taking zolpidem during pregnancy were compared with outcomes in a group of 45 women who were matched for age, race, level of education, SCID diagnosis, and pregnancy exposure to the same classes of nonzolpidem psychotropic medications.
For women who took zolpidem during pregnancy, exposure by trimester included 38% in the first trimester, 56% in the second trimester, and 38% in the third trimester. The average zolpidem exposure during pregnancy was 14 weeks, and the average dose was 9 mg.
There were no statistically significant differences between the two groups in terms of obstetrical and neonatal outcomes. However, there was a trend toward preterm delivery and low-birth-weight infants in women on zolpidem during pregnancy. In that group, 27% of the women had a preterm delivery and 16% had low-birth-weight infants, compared with 16% and 8%, respectively, for the nonzolpidem group.
“It is unclear if these outcomes were driven by zolpidem exposure and/or sleep disturbance or other pharmacological intervention in pregnancy,” wrote Sandra Juric and colleagues at Emory University's Women's Mental Health Program, Atlanta.
Women who reported longer zolpidem use during pregnancy (10 weeks or longer) did not have a greater rate of complications. There also appeared to be no difference between drug use in a particular trimester versus use throughout the pregnancy in terms of complications. Ms. Juric reported no conflicts of interest.