When the trial began, there were limited
safety data on tenofovir in pregnancy, and randomization to tenofovir-based ART was limited
to women coinfected with HIV and HBV, because
benefit was felt to outweigh risk in that group;
comparative analyses including the group assigned to tenofovir-based ART were to be limited
to a nested HBV substudy. During period 1 (April
2011 through September 2012), women without
HBV coinfection were assigned only to zidovudine alone or zidovudine-based ART. However,
in October 2012, with increased data on tenofovir