Children born to women who take the HIV drug efavirenz during pregnancy have a higher risk of small head size – a birth defect known as microcephaly – compared to babies exposed to other HIV drugs in the womb, new research shows.
Prenatal exposure to the drug was also linked to developmental delays in children.
Limited impact of findings
But one US expert said the new data shouldn't alarm most HIV-positive women.
"Efavirenz has not been widely used in the US during pregnancy for many years due to its association with neural tube defects in studies conducted in monkeys," said Dr Joseph McGowan, medical director of the Northwell Health HIV Service Line Program in Manhasset, New York.
"Antiretroviral usage patterns have shifted away from efavirenz as recommended therapy, so the impact of these findings in the US and developed countries may be limited," said McGowan, who wasn't involved in the new study.
"The major take-home from this study for me was that use of antiretrovirals during pregnancy was found to be safe for the exposed, uninfected infant with the one exception of efavirenz," he added. "This should be reassuring to clinicians and mothers."
The new research was led by Dr Rohan Hazra, chief of the maternal and paediatric infectious disease branch at the US National Institute of Child Health and Human Development.
Hazra's team tracked data from more than 3 000 children born to US women who took HIV drugs during pregnancy. The children's head circumferences were measured from age six months through five to seven years of age.
Lower development scores
The children's head growth was assessed using two classification systems: one developed by the US Centers for Disease Control and Prevention for children under three years of age, and Nellhaus charts, which are used for children older than three years.
The study couldn't prove cause and effect. But based on Nellhaus charts, children whose mothers took the HIV drug efavirenz were more than twice as likely to have microcephaly than those whose mothers took other HIV drugs.
Based on the combined Nellhaus-CDC standards, children exposed to efavirenz in the womb were around 2.5 times more likely to have microcephaly than those exposed to other HIV drugs in the womb.
Children with microcephaly based on Nellhaus charts also scored lower on standardised tests of development at ages one and five years.
Of the 141 children exposed to efavirenz in the womb, 14 (9.9%) had microcephaly, compared to 142 of 2 842 who were not exposed to efavirenz (5%), according to the US National Institutes of Health-funded study published online recently in The Lancet HIV.
"Our findings underlie the importance of having alternatives to combination therapy with efavirenz for pregnant women with HIV," Hazra said in an NIH news release.
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