Elevated frequencies of micronucleated erythrocytes in infants exposed to zidovudine in utero and postpartum to prevent mother-to-child transmission of HIV

Zidovudine-based antiretroviral therapies (ART) for treatment of HIV-infected pregnant women have markedly reduced mother-to-child transmission of the human immunodeficiency virus (HIV-1) from ~25% to <1%. However, zidovudine (ZDV; AZT), a nucleoside analogue, induces chromosomal damage, gene mutations, and cancer in animals following direct or transplacental exposures. To determine if chromosomal damage is induced by ZDV in infants exposed transplacentally, we evaluated micronucleated reticulocyte frequencies (%MN-RET) in 16 HIV-infected ART-treated mother-infant pairs. Thirteen women received prenatal ART containing ZDV; 3 received ART without ZDV. All infants received ZDV for 6 weeks postpartum. Venous blood was obtained from women at delivery, and from infants at 1–3 days, 4–6 weeks, and 4–6 months of life; cord blood was collected immediately after delivery. Ten cord blood samples (controls) were obtained from infants of HIV-uninfected women who did not receive ART. %MN-RET was measured using a single laser 3-color flow cytometric system. Ten-fold increases in %MN-RET were seen in women and infants who received ZDV-containing ART prenatally; no increases were detected in 3 women and infants who received prenatal ART without ZDV. Specifically, mean %MN-RET in cord blood of ZDV-exposed infants was 1.67±0.34 compared with 0.16±0.06 in non-ZDV ART-exposed infants (P=0.006) and 0.12±0.02 in control cord bloods (p