To determine the clinical course and perinatal transmission of chronic hepatitis B during pregnancy in a real life setting.

A total of 221 singleton pregnant women with detectable HBV-DNA levels (≥10³ copies/mL) were enrolled during January 2011 to June 2015. Forty-three high viraemic patients (≥10⁶ copies/mL) received telbivudine in the 2^nd or 3^rd trimester according to their intention, while 89 high viraemic and 79 low viraemic (≥10³ and <10⁶ copies/mL) patients were the control cohorts. Primary endpoint was the pregnancy outcomes and secondary endpoint the perinatal transmission including intrauterine infection, immunoprophylaxis failure and occult infection.

In all, 209 patients completed pregnancy with 209 infants, while 2 in telbivudine-treated cohort had unexplained late stillbirths. Twenty-nine (70.7%) of telbivudine-treated patients and 3 (3.4%) of untreated high viraemic controls achieved undetectable HBV-DNA levels prior delivery. At 7 months postpartum, immunoprophylaxis failure was significantly lower (2.4%) in telbivudine-treated cohort, compared with 16.9% and 10.1% in untreated high and low viraemic cohorts, respectively.

Low viraemic patients may also need antiviral therapy since they bear moderate risk for perinatal transmission of HBV. However, more multicenter, large-scale studies are required before antepartum antiviral therapy is routinely recommended in patients with detectable viral loads.