Anti-viral therapy for prevention of perinatal HBV transmission: extending therapy beyond birth does not protect against post-partum flare

Background Antepartum anti-viral therapy (AVT) is often administered to prevent perinatal transmission of hepatitis B virus (HBV) infection. Little is known about the effect of AVT on post-partum flare rates and severity. Aim To examine whether extending AVT beyond birth influences the post-partum course. Methods One hundred and one pregnancies in 91 women with HBV DNA levels >= log 7IU/mL were included. AVT (initially lamivudine, later tenofovir disoproxil fumarate) was commenced from 32weeks gestation and stopped soon after birth and at 12weeks post-partum. Outcomes according to post-partum treatment duration were examined: Group 1=AVT <= 4weeks (n=44), Group 2=AVT >4weeks (n=43), Group 3=no AVT (n=14). Results The majority of women were HBeAg+ (97%), median age 29years, baseline HBV DNA log 8.0IU/mL and follow-up 48weeks post-partum. Post-partum treatment duration was 2weeks for Group 1 and 12weeks for Group 2, P<0.01. Flare rates were not significantly different: Group 1=22/44 (50%), Group 2=17/43 (40%) and Group 3=4/14 (29%), P=0.32. Onset of flare was similar at 8/10/9weeks post-partum for Groups 1/2/3 respectively, P=0.34. The majority of flares spontaneously resolved. HBeAg seroconversion (n=1/5/1 in Groups 1/2/3, P=0.27) was not associated with treatment duration or the occurrence of a post-partum flare. Conclusions Post-partum flares are common and usually arise early after delivery. They are often mild in severity and most spontaneously resolve. Extending anti-viral therapy does not protect against post-partum flares or affect HBeAg seroconversion rates.