Occurrence of hepatitis B in pregnant women and follow-up of exposed children in the State of São Paulo, Brazil, in 2012.

Objective: to describe the occurrence of hepatitis B among pregnant women, immunoprophylaxis and vertical and perinatal transmission in children exposed to the virus in the São Paulo state primary care network, Brazil.
Methods: this was a cross-sectional study using prenatal records of pregnant women attending health services between January and June 2012 and a cohort of newborns; the frequencies of the results were described and the estimated occurrence of hepatitis B was calculated.
Results: 6,233 pregnant women were included, of whom 53.1% were between 20-29 years old, 58.7% had 8-11 years of schooling, 53.3% were white, and 73.9% lived with a partner; occurrence of hepatitis B was 0.13% (95%CI 0.04; 0.21); of the eight children of mothers with chronic hepatitis B, six had a complete vaccination schedule, and there was no vertical or perinatal transmission.
Conclusion: there was low occurrence of hepatitis B in pregnant women and absence of vertical or perinatal transmission.