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A normal pregnancy lasts about 40 weeks from the first day of your last menstrual period to the
birth of a baby. This time is roughly divided into 3 periods: the first
trimester, from the first day of your last menstrual period to about the 12th week of pregnancy; the second
trimester, from about 13 to 27 weeks of pregnancy; and the third trimester,
from about 28 weeks of pregnancy until birth.
Each trimester of pregnancy is marked by developmental changes in
Current as of:
May 30, 2016
Sarah Marshall, MD - Family Medicine & Kirtly Jones, MD - Obstetrics and Gynecology
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