In Utero Tenofovir Exposure Is not Associated With Fetal Long Bone Growth

Despite widespread use of tenofovir disoproxil fumarate (TDF) in pregnant and breastfeeding women, few data exist on fetal bone development after in utero TDF exposure. We evaluated fetal long bone growth in human immunodeficiency virus (HIV)-infected pregnant woman/fetus dyads in Cape Town, South Africa.

Women were recruited from primary care antenatal services and underwent ultrasonography to determine femur (FLZ) and humerus (HLZ) length z scores. The duration of in utero TDF exposure was calculated in weeks. Linear regression models were applied to assess the associations between the duration of in utero TDF exposure and change in FLZ and HLZ.

A total of 646 woman/fetus dyads contributed 1376 ultrasonographic scans to this analysis: 132 dyads with ≥25 weeks, 326 with 10-24 weeks, and 188 with <10 weeks of TDF exposure. Women receiving TDF for ≥25 weeks were older than those receiving TDF for 10-24 or <10 weeks (median age, 31 vs 28 and 28 years, respectively; P < .01), and had lower HIV RNA levels (median log10 HIV RNA level, 1.59 vs 4.08 and 3.83, respectively; P < .01). Throughout gestation, overall median FLZ and HLZ were 0.30 (interquartile range, -0.03 to 0.63) and 0.22 (-0.26 to 0.59) respectively. In multivariate analysis, there was no association between duration of in utero TDF exposure per 1-week increment and change in FLZ (ß = .00; P = .51) or change in HLZ (ß = .00; P = .40). Results were similar using mixed-effects models.

Although longer follow-up is needed, these in utero data are reassuring and support the continued use of TDF in pregnancy.