A normal pregnancy lasts around 37-42 weeks, or an average of 40 weeks from the 1st day of your last period. Pregnancy is often divided into thirds, called trimesters. It's a useful way to help describe the changes that happen during pregnancy. The 1st trimester is week 1- week 12, the 2nd is week 13 - week 27, and the 3rd is week 28 - week 40.
Attribution: BUPA
See also:
- The fetus in 1st trimester
- Organ development in 2nd trimester
- When do baby lungs mature
- More signs of pregnancy