Pregnancy outcomes are similar for women treated with efavirenz and nevirapine during the first trimester, investigators from Ivory Coast report in the online edition of the Journal of Acquired Immune Deficiency Syndromes.
No birth abnormalities were observed in children exposed to either drug. However, women taking efavirenz were more likely than those treated with nevirapine to have their pregnancy terminated.
“Our study…is the single largest study to date evaluating HIV-infected women exposed to efavirenz during the first trimester of pregnancy,” write the authors; “no increased risk of pregnancy outcomes was reported following efavirenz exposure compared to nevirapine exposure during the first trimester.”
Non-nucleoside-reverse transcriptase inhibitors (NNRTIs) are recommended for first-line HIV treatment in resource-limited settings. Efavirenz is the preferred drug because it has fewer side-effects than nevirapine.
There have been observations of birth abnormalities in the offspring of animals exposed to efavirenz in the first trimester of pregnancy. Although WHO guidelines state that women should avoid taking the drug at this time, large studies have shown that therapy with efavirenz early in pregnancy does not increase the risk of birth abnormalities.
Little is known about the comparative impact of efavirenz and nevirapine on other birth outcomes, such as stillbirth, prematurity and low birth-weight.
Therefore investigators from Ivory Coast undertook a retrospective study including 344 women who became pregnant when taking either of these drugs between 2003 and 2009.
These women had a median age of 29, and their median CD4 cell count at the time they started antiretroviral therapy was 217 cells/mm3.
Most of the women (213) were taking efavirenz at the time they conceived, and the majority (190, 89%) of those taking efavirenz changed treatment(165 to nevirapine, the others to a protease inhibitor). The median duration of follow-up for women taking efavirenz was 52 days, significantly shorter than the 264 days for those treated with nevirapine.
Pregnancy outcomes were known for 326 women. Overall, 12% had a termination, 5% miscarried, and 7% had a stillbirth. Women taking efavirenz were significantly more likely than those treated with nevirapine to have a termination (14 vs 7%, p = 0.05).
“This high frequency of abortion after early efavirenz exposure could be related to the fear of warning given by clinicians about the potential risk of congenital abnormalities,” suggest the authors.
There were 249 live births, and 11% of infants were born prematurely. The rate of pre-term delivery did not differ significantly between efavirenz and nevirapine (10 vs 13%).
Overall, 20% of infants had a low birth-weight, and comparable rates of this outcome were seen in the women exposed to either drug (efavirenz, 17% vs nevirapine, 24%).
No infant had a birth abnormality. The investigators believe that their study adds to the growing body of literature showing the safety of efavirenz during pregnancy.
They conclude that the results of their study are “reassuring”, but they call for “more collaborative studies and pharmacovigilance systems capturing routine data…to improve the evidence informing public health guidelines.”
Ekouevi DK et al. Pregnancy outcomes in women exposed to efavirenz and nevirapine: an appraisal of the IeDEA West Africa and ANRS databases, Abidjan, Côte d’Ivoire. J Acquire Immune Defic Syndr, online edition: DOI: 10. 1097/QAI.0b013e3181ff4e6, 2010 (for the free abstract click, here).