Universal antenatal screening of hepatitis B virus (HBV) infection in an endemic region has revealed that the infection rate was correlated with gravidity and parity. There are similarities in the immunological alterations between a successful pregnancy and the immune tolerant phase of chronic HBV infection which is often acquired in the perinatal and infancy period, such that female carriers are usually healthy with minimally affected pregnancy outcomes. Furthermore, there are reduced pre-eclampsia and small-for-gestational age, but increased birth weight and large-for-gestational age/macrosomic infants which can mitigate the increased perinatal and infant mortality from growth restriction and low birth weight. Chronic HBV infection per se is not associated with female infertility, while this may even enhance the success rate of in-vitro fertilization treatment in infertile women. HBV can also be found in the ovary, which could transmit the infection to the offspring and result in neonatal immunoprophylaxis failure. Although HBV can cause hepatic cirrhosis and carcinoma, these conditions usually manifest in late adulthood and after the menopause, and hence HBV infection in women is not detrimental to human reproduction. HBV is found in various body fluids, which can lead to horizontal transmission especially in the household setting, and this probably plays an important role in sustaining high endemicity despite measures to prevent vertical transmission. Successful vertical transmission can create a founder effect, which can be augmented by horizontal transmission and these processes together have probably promoted its transmission through successive generations of humans in a successful symbiotic relationship for the past 100,000 years.