Zidovudine inhibits telomere elongation, increases the transposable element LINE-1 copy number and compromises mouse embryo development.

AZT at concentrations approaching those used to prevent perinatal HIV transmission compromises mouse embryo development, prevents telomere elongation and increases LINE-1 copy number after 48 h treatment. The impact of these effects on the trajectory of aging of children exposed to AZT early during development deserves further investigation.