Pregnant women experience unique physiological changes that may result in clinically significant alterations in drug PKs. Unfortunately, there have been few clinical trials to study the PKs of ARV, TB, and hormonal contraceptive drugs in pregnant women. The development of appropriate dosing regimens for the HIV-infected pregnant woman is critical to the health of both mother and fetus. Overdosing may lead to maternal adverse events and increased risk of fetal toxicity, while underdosing may lead to inadequate virologic control, increased risk of developing drug resistance mutations, and a higher rate of perinatal HIV transmission. This study will evaluate the PKs of ARVs used during pregnancy; evaluate TB drugs used during pregnancy, both in women who are HIV-positive and also taking ARVs and in women who are HIV-negative and not taking ARVs; and evaluate the PKs of hormonal contraceptive medications taken along with ARVs.