Which combination is not preferred for initial antiretroviral therapy in pregnant women?

The combination of zidovudine and stavudine is not preferred for initial antiretroviral therapy in pregnant women primarily due to concerns about safety and efficacy. Zidovudine is indeed one of the standard treatments for HIV in pregnancy, as it has a long history of use and established efficacy in reducing the risk of perinatal transmission. However, stavudine is less favored because it has been associated with more side effects and has fallen out of favor compared to other nucleoside reverse transcriptase inhibitors (NRTIs) like abacavir and lamivudine, which have better tolerability and are safer for both the mother and the fetus.

Additionally, the use of stavudine can lead to lipoatrophy and other metabolic complications, which are particularly concerning during pregnancy when maternal health is paramount. The other combinations, which include atazanavir with ritonavir, darunavir with ritonavir, and abacavir with lamivudine, are considered better options due to their safety profiles and effectiveness in maintaining viral suppression during pregnancy, as well as their generally favorable side effect profiles.