[Factors associated with virological response in women receiving highly-active antiretroviral prophylaxis for HIV-1 mother-to-child transmission].

Introduction: Pregnancy is the only circumstance in HIV infection requiring urgent virological response to the antiviral approach because of the influence of plasma viral load (VL) on mother-to-child transmission (MCT) of the disease. This study analyzes factors related to the time needed to reach VL < 400 copies/mL during antiretroviral prophylaxis for MCT.

Methods: The study included a cohort of HIV-1 infected pregnant women enrolled between 2000 and 2005 with baseline CD4+ lymphocyte count > 300 cells/microL, highly-active antiretroviral prophylaxis for at least 4 weeks, antiretroviral interruption after delivery, and available laboratory data.

Results: Seventy-five pregnancies were analyzed. Median baseline VL was 3.71 log(10) copies/mL and CD4+ count was 573 cells/microL. Prophylaxis started after 26.6 weeks of gestation and lasted up to 11.7 weeks in 75% of cases. The prophylactic regimen was changed in 12 pregnancies, 7 because of toxicity. A protease inhibitor was included in 33 prophylactic regimens, 11 of them with lopinavir. Prophylaxis resulted in undetectable HIV-1 VL within 6.7 weeks in 75% of pregnancies. VL was detectable at the end of prophylaxis in 5 cases. Time to undetectable VL was shorter if baseline VL was less than 100,000 copies/mL and the antiretroviral regimen was not changed during prophylaxis.

Conclusions: To achieve VL < 400 copies/mL at delivery, antiretroviral prophylaxis should be started before 26 to 28 weeks of pregnancy. A potent and well-tolerated prophylactic antiretroviral regimen will likely reduce the time to virological response. Trials investigating alternative regimens (e.g., lopinavir-containing) for patients with late diagnosis during prenatal care or VL >100,000 copies/mL are warranted.