Highest transmission of hepatitis B from mother to fetus occurs if the mother is infected during which phase of the pregnancy?

Highest transmission of hepatitis B from mother to fetus occurs if the mother is infected during 3rd trimester (90%). Transmission is high from those mothers who are seropositive to hepatitis B surface antigen (HBsAg) and HbeAg. Risk of transmission is only 10% in first trimester. Hepatitis B virus is transmitted by parenteral route, sexual contact, veical transmission and also through breast milk. Neonatal transmission mainly occur at or around the time of bih through mixing of maternal blood and genital secretions. It can be diagnosed by the detection of HBsAg and HBeAg and antibody to hepatitis B core antigen (HBcAg). They are at high risk of developing chronic active hepatitis, cirrhosis and hepatocellular carcinoma. Ref: Textbook of Obstetrics By D. C Dutta, 6th Edition, Page 291-2