Had sex for 2 weeks but… 4 weeks gestation?!?

Calculating gestational age based on the date of conception is an age-old method with considerably lower accuracy compared to modern methods. So, is it accurate to have had intercourse two weeks ago and yet the gestational age is calculated as four weeks? Let’s hear from leading Obstetricians – Van Huy Ha, Resident Physician; Tran Bao Chau, MD, Specialist Level 2; Quoc Bao Tran, MD, as they explain this issue.