The use of highly active antiretroviral treatment during pregnancy is now standard care to prevent mother-to-child HIV transmission in developed countries. There is controversy about its impact on low birth weight. Briand and colleagues set out to evaluate the impact of antiretroviral therapy during the pregnancy on birth weight, length, and head circumference. The study was performed in uninfected infants born to HIV-1-infected mothers, enrolled from 1990 to 2006 in the Agence Nationale de Recherches sur le SIDA French Perinatal Cohort CO1. The authors excluded mothers who used illicit drugs during pregnancy or had no prenatal care before the third trimester, twins and stillbirths. They used Z-scores adjusted for gestational age and sex. In 8192 mother-infant pairs, the mean birth weight Z-scores increased between 1990 and 1997 and then remained stable until 2006. There was no significant relation between the type of antiretroviral therapy and the proportion of small for gestational age (birth weight Z-score