Is the interruption of antiretroviral treatment during pregnancy an additional major risk factor for mother-to-child transmission of HIV type 1?

Background: There is currently an experts' agreement discouraging interruption of antiretroviral treatment (ART) during the first trimester of pregnancy in women infected with human immunodeficiency virus type 1 (HIV-1). However, this recommendation is poorly supported by data. We evaluated the effects of discontinuing ART during pregnancy on the rate of mother-to-child transmission.

Methods: Logistic regression models were performed in a prospective cohort of 937 children who were perinatally exposed to HIV-1 to estimate adjusted odds ratios for confounding factors on mother-to-child transmission, including maternal interruption of ART.

Results: Among 937 pregnant women infected with HIV-1, ART was interrupted in 81 (8.6%) in the first trimester and in 11 (1.2%) in the third trimester. In the first trimester, the median time at suspension of ART was 6 weeks (interquartile range [IQR], 5-6 weeks) and the time without treatment was 8 weeks (IQR, 7-11 weeks). In the third trimester, the median time at suspension of ART was 32 weeks (IQR, 23-36 weeks) and the time without treatment was 6 weeks (IQR, 2-9 weeks). The plasma viral load was similar in women who had treatment interrupted in the first trimester and in those who did not have treatment interrupted. Overall, the rate of mother-to-child transmission in the whole cohort was 1.3% (95% confidence interval [CI], 0.7%-2.3%), whereas it was 4.9% (95% CI, 1.9%-13.2%) when ART was interrupted in the first trimester and 18.2% (95% CI, 4.5%-72.7%) when ART was interrupted in the third trimester. In the multiple logistic regression models, only interruption of ART during either the first or the third trimester, maternal mono- or double therapy, delivery by a mode other than elective cesarean delivery, and a viral load at delivery >4.78 log(10) copies/mL were independently associated with an increased rate of mother-to-child transmission.

Conclusions: Discontinuing ART during pregnancy increases the rate of mother-to-child transmission of HIV-1, either when ART is stopped in the first trimester and subsequently restarted or when it is interrupted in the third trimester. This finding supports recommendations to continue ART in pregnant women who are already receiving treatment for their health.