This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical, surgical and gynaecological illness complicating pregnancy, Subject name: Gynaecology & Obstetrics
[{'content': 'Highest transmission of hepatitis B from mother to fetus occurs, if the mother is infected during: \nSelect and explain. \nA. 1st trimester, B. IInd trimester, C. IIIrd trimester, D. At the time of implantation', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The virus is transmitted by parenteral route, sexual contact, veical transmission and rarely breast milk. The risk of transmission to fetus ranges from 10% in 1st TM to as high as 90% in 3rd TM. It is specifically high (90%) from those mothers who are seropositive to hepatitis B surface Antigen(HBsAg) and e-antigen(HBeAg) Reference: Textbook of Dutta,9th edition, page 271', 'role': 'assistant'}]