RESUMEN
OBJECTIVES: To determine the prevalence and type of birth defects among infants following exposure to efavirenz-based antiretroviral therapy (EFV-based ART) during pregnancy. METHODS: A Pregnancy Registry was established to enable prospective follow-up of women taking EFV-based ART. In women who conceived on EFV-based ART, EFV was switched with another drug if they presented during the first trimester but was continued if they presented at or after 14 weeks' gestation. Pregnant women needing lifelong ART were commenced on EFV-based ART from 14 weeks' gestation onwards. Infants were followed up for 6 weeks after birth. RESULTS: Between January 2006 and December 2008, 623 ART-naive pregnant women initiated EFV-based ART in the second/third trimester and 195 women conceived on EFV-based ART. Birth defects were observed in 16 of 623 live births [2.6%; 95% confidence interval (CI) 1.5-4.2] and in six of 184 live births (3.3%; 95% CI 1.2-7.0) from women exposed to EFV in the second/third trimester and first trimester, respectively. The prevalence of birth defects was not significantly different between the first and second/third trimester EFV exposure (prevalence ratio 1.27; 95% CI 0.50-3.20; P = 0.301). CONCLUSION: No significant increase in the prevalence of birth defects following exposure to EFV-based ART in the first trimester was observed in this cohort. However, the limited number of first trimester EFV-exposed infants precludes definitive conclusions on the teratogenicity or safety of EFV.