Combination antiretroviral therapy and duration of pregnancy.

To assess the association between type and timing of initiation of antiretroviral therapy in pregnancy and duration of pregnancy. Prospective study. Data on 3920 mother-child pairs were examined (3015 mother-child pairs from the European Collaborative Study and 905 from the Swiss Mother + Child HIV Cohort Study). Factors examined included gestational age, antiretroviral therapy during pregnancy, maternal CD4 count, viral load, illicit drug use (IDU) and mode of delivery. Deliveries at less than 37 weeks were defined as premature. The prematurity rate was 17% and median gestational age 39 weeks. Twenty-three per cent (896 of 3920) of women received antiretroviral therapy during pregnancy: 64% (573 of 896) zidovudine monotherapy, 24% (215) combination therapy without protease inhibitors (PI) and 12% (108) combination therapy with PI. In multivariate analysis, adjusted for maternal CD4 count and IDU, odds ratio (OR) of prematurity was 2.60 [95% confidence interval (CI), 1.43-4.75] and 1.82 (95% CI, 1.13-2.92) for infants exposed to combination therapy with and without a PI, respectively, compared to no treatment. Exposure to monotherapy was not associated with prematurity, but severe immunosuppression and IDU in pregnancy were. Women on combination therapy from before pregnancy were twice as likely to deliver prematurely as those starting therapy in the third trimester (OR, 2.17; 95% CI, 1.03-4.58). Pregnancy issues should be discussed when making decisions about initiation of combination antiretroviral therapy for HIV-infected women. Elective caesarean section to reduce vertical transmission at 36 weeks rather than 38 weeks may be advisable in women on combination therapy with PI.