Hanoi was selected as the study site because comprehensive PMTCT care is theoretically available there. Hanoi had 45 hospitals, 290 surgeries and five international hospitals. The national hospitals in Hanoi serve as referral centres for the northern half of Viet Nam. HIV testing and counselling for pregnant women are offered at health facilities at district or higher level, but often only after the 28 th week of gestation. HIV-positive women are referred to provincial or national hospitals for ARV prophylaxis, delivery and postnatal care. Hanoi health services have sufficient supplies of prophylactic ARV to meet the demand. Antiretroviral therapy for adults is available at district level or higher. HIV-exposed infants are offered polymerase chain reaction (PCR) testing and free infant feeding formula for at least six months, while free paediatric ARV is available for children three years of age or older.