Use of Anti-HIV Drug Does Not Effect Birth Size

June 4, 2012

The use of the anti-HIV drug tenofovir during pregnancy does not affect birth weight or birth length, according to new research conducted as part of the Pediatric HIV/AIDS Cohort Study. The impetus for this study was that previous research in laboratory animals showed that exposure to tenofovir in the womb was associated with smaller birth size compared with animals not exposed to the drug.

The use of the anti-HIV drug tenofovir during pregnancy does not affect birth weight or birth length, according to new research conducted as part of the Pediatric HIV/AIDS Cohort Study.1 The impetus for this study was that previous research in laboratory animals showed that exposure to tenofovir in the womb was associated with smaller birth size compared with animals not exposed to the drug.

From 2003 to 2010, the researchers collected data from 2029 children who were exposed in the womb to anti-HIV drug regimens either with or without tenofovir.1 The association of maternal tenofovir use during pregnancy with size for gestational age, low birth weight, weight for age, length for age, and head circumference was then compared. At birth, no significant differences between infants exposed to combination regimens with tenofovir and infants exposed to regimens without tenofovir were found. At 1 year of age, however, infants exposed to combination regimens that included tenofovir were shorter and had smaller head circumferences compared with infants exposed to regimens that did not include tenofovir. On average, the infants born to mothers with HIV infection were smaller than infants born to mothers without HIV infection.

The study authors consider their findings to be reassuring, especially because use of tenofovir in pregnant women with HIV infection is becoming more common. In the study, the percentage of mothers that had been prescribed tenofovir was 14% in 2003, compared with 43% in 2010.1 Before this study, tenofovir had not been studied specifically for potential effects on infants. The study authors also note that no serious safety concerns regarding use of tenofovir during pregnancy were identified.

“Although further research is needed, on balance, our findings favor the use of tenofovir in pregnancy to ensure good outcomes in the mother and prevent transmission of HIV to the infant,” said George Siberry, MD, first author of the study.2

Pertinent Points:
- Tenofovir is safe to use during pregnancy, although the drug may be associated with a delayed growth effect.
- Infants exposed to tenofovir in the womb are not smaller or shorter than infants exposed to other anti-HIV medications in the womb. However, tenofovir-exposed infants are smaller at their first birthday.

References:

References
1. Siberry GK, Williams PL, Nendez H, et al, for the Pediatric HIVAIDS Cohort Study (PHACS). Safety of tenofovir use during pregnancy: early growth outcomes in HIV-exposed uninfected infants. AIDS. 2012;26:1151-1159.
2. U.S. Department of Health and Human Services, National Institutes of Health. Anti-HIV drug use during pregnancy does not affect infant size, birth weight. Available at: http://www.nih.gov/news/health/may2012/nichd-01.htm. Accessed May 21, 2012.