Antiretroviral treatments are an effective way of protecting babies against HIV transmission from mothers. However, a new study has highlighted the intense side-effects possible with the ART drug efavirenz, which may include microcephaly.
This new research article published in The Lancet HIV journal found that the use of efavirenz by pregnant women might lead to an increased risk of microcephaly for the infant. In turn, kids with microcephaly were at a higher risk for developmental delays as compared to kids with normal head size. 
These conclusions were drawn for the drug efavirenz and not for any other drugs used as a part of the antiretroviral therapy, used to help people living with HIV infections and reduce the risk of HIV transmission.
“Our findings underline the importance of having alternatives to combination therapy with efavirenz for pregnant women with HIV,” said study author Rohan Hazra, M.D., chief of the Maternal and Pediatric Infectious Disease Branch of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, which provided funding for the study. 
Microcephaly is a condition where the circumference of the head of a child is smaller than the expected size, usually due to abnormal brain development. The team of researchers analyzed the data from a follow-up study of over 30,000 infants born to women on HIV therapy during pregnancy. The head growth of these children was measured and further classified and ranked using the Nellhaus Charts.
Known side effects of efavirenz, commonly available under the brand name ‘Sustiva’, include mental health problems, liver problems, and potential risk of birth defects when taken by pregnant women.