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.
Primary Medical ReviewerSarah Marshall, MD - Family Medicine
Specialist Medical ReviewerKirtly Jones, MD - Obstetrics and Gynecology
Current as ofSeptember 9, 2014
WebMD Medical Reference from Healthwise