Safe administration of drugs in pregnancy may require dose adjustment due to the pregnancy-induced physiologic alternations. Therefore, careful pharmacokinetic (PK) evaluation is a critical first step to ensure safe administration of drugs to both the mother and the developing fetus. This is a single-arm, single-center, open label Phase 1 evaluation of the PK and safety of treating HCV with a 12 week course of LDV/SOF in 15 HCV-infected pregnant women. Therapy will be initiated at approximately 24 weeks of gestation. In this study we will determine: 1) if the PK of the LDV and SOF are similar in pregnancy as compared to those in nonpregnant women, 2) if the viral response to LDV/SOF treatment in pregnancy is similar to that observed in nonpregnant women, and 3) if there are any initial maternal or neonatal safety concerns detected with antenatal LDV/SOF administration compared with HCV-infected historical controls delivered at our institution. From the findings of this study, future studies will seek to optimize the dose, gestational age timing and treatment duration of LDV/SOF during pregnancy. Antenatal HCV treatment will improve maternal health, prevent further HCV transmission in the community and perinatal HCV transmission to the child, and thus enhance the long-term health of two generations.