The purpose of this study is to evaluate the safety of administering a combination vaccine (DTaP-HepB-IPV; Pediarix™) to infants at birth, 2 and 6 months compared to the administration of a HepB vaccine at birth and the same combination vaccine at 2, 4, and 6 months of age. Additionally, researchers will assess the body's antibody response (proteins produced by the body's immune system that help fight infections) following each vaccine dose. The study will enroll 5 healthy newborns, ages 0-5 days. Participants will be involved in study related procedures for up to 288 days, including blood sample collection and 5 study visits.