Infants whose mothers took atazanavir had small but significant effects on language and social-emotional development, compared to other non-atazanavir-containing antiretroviral regimens, a study published in AIDS has shown. 

Atazanavir is a protease inhibitor drug sometimes included in antiretroviral regimens to prevent maternal-fetal HIV transmission during pregnancy. Previous studies suggested possible delay in language development in infants whose mothers received atazanavir during pregnancy. Scientists from the Pediatric HIV/AIDS Cohort Study (PHACS) group evaluated data on 917 infants who were born to HIV-positive mothers but did not acquire HIV infection. All mothers took antiretroviral therapy during pregnancy to reduce the risk of HIV transmission. 

RELATED: Recommendations for ART Dosing During International Travel

When the infants were about 1 year old, they were assessed on the Bayley Scales of Infant and Toddler Development – Third Edition (Bayley III, a standard infant development test. Bayley III subscale scores were compared for 167 infants whose mothers took atazanavir-containing regimens vs. 750 infants whose mothers took received antiretroviral therapy that did not contain atazanavir. 

Researchers found lower language development scores for infants whose mothers took atazanavir, particularly in mothers who initiated therapy in the first trimester as well as during the second or third trimesters. Scores were about 3 points lower in the atazanavir-exposed infants group, compared to an average score of 93. 

Lower scores for social-emotional development were also seen in infants whose mothers took atazanavir. The difference in scores was only significant among infants whose mothers initiated therapy during the second or third trimesters and not the first trimester. Scores were about 5 points lower in the atazanavir-exposed infants group, compared to an average score of 100. 

Scores for cognitive, motor (movement), and adaptive behavior were similar for infants exposed and unexposed to atazanavir. The average scores were within normal range for all Bayley III subscales. Researchers concluded more studies are needed to assess whether these differences last beyond age 1. Additional issues to address include the mechanism of atazanavir in which these developmental effects occur and whether there is an association to the drug tenofovir, which is commonly used with atazanavir. 

For more information visit