Long-term safety and efficacy of telbivudine in infants born to mothers treated during the second or third trimesters of pregnancy.

Telbivudine, an FDA pregnancy category B drug, has been found to reduce hepatitis B virus (HBV) perinatal transmission with no safety concerns in infants aged up to 1 year. This study evaluated the long-term efficacy and safety of telbivudine in 214 infants born to 210 pregnant women with chronic hepatitis B infection who were treated with telbivudine during pregnancy (weeks 20-32 of gestation). The infants were followed for up to 5 years after birth. The efficacy endpoint was the rate of perinatal transmission, which was established by HBsAg and HBV DNA levels at 7 and 12 months. Safety endpoints included head circumference, weight, height, congenital abnormality and hospitalization rates. In addition, the Denver Developmental Screening Test was performed in 92 randomly selected infants. None of the 214 infants born to these women were infected with HBV, and all had effective serum hepatitis B surface antibody (HBsAb) levels. Compared with Chinese standard values, there were few differences in the infants' mean head circumference, weight, and height values. No birth defects were diagnosed, and the congenital abnormality rate was 0.934%. Serious adverse events requiring hospitalization occurred in 20 infants (9.35%). The qualified Denver Developmental Screening Test rate in 92 infants was 97.82%, which was comparable to a rate of 92% in normal Chinese children. Thus, treatment with telbivudine during the second or third trimesters of pregnancy safely blocked perinatal transmission of HBV. Infants born to telbivudine-treated mothers showed normal growth and development during long-term follow-up of up to 5 years.