Human pregnancy can be divided into three trimesters, each three months long. The first trimester is from the last period to the 13th week, the second trimester is from the 14th to 27th week, and the third trimester is from the 28th week through the 40th week.
In humans, birth normally occurs at a gestational age of about 40 weeks, though a normal range is from 37 to 42 weeks. Childbirth occurring before 37 weeks of gestation is considered preterm, whereas childbirth after 42 weeks is considered postterm. Preterm and low birth weight babies make up the second leading cause of infant death at about 17%. Preterm births solely consist of 12% of infant deaths with an 84% majority within the 32-36 week period.
This answer was edited by USAFRET91 164 days ago.
Reason: Corrected spelling
