Fetal and Pregnancy Dates
Fetal and pregnancy dates are not the same—when a woman is 24 weeks pregnant, her growing baby (fetus) is about 22 weeks old. This is because the start of the pregnancy is counted from the first day of her last menstrual period (LMP), but the embryo doesn't start growing until about 2 weeks later.
Current as of: May 1, 2026
Author:
WebMD Ignite Staff
Clinical Review Board
All WebMD Ignite education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.