26/12/2020
Revealing the 100 secrets of unborn baby:
41st secret of unborn baby
Since 1836, doctors have marked the first day of a woman's last menstrual period as the first day of pregnancy, or gestational age, not when a s***m fertilizes an egg.
Ovulation happens about two weeks after a period, on average, and fertilization happens within 24 hours of that. This means if you're eight weeks pregnant, your baby is about 15 days younger than that. Doctors still use gestational age, not ovulation age (also called postconceptional age) because it's hard to detect ovulation and fertilization even more so. Periods, meanwhile, are hard to miss — and easier to notice when they've gone missing.
Sources: American Pregnancy Association, “Williams Obstetrics”, Business Insider
41st secret of the unborn baby