The word "trimester" in Latin means "three months". This division of the gestational age allows you to break 40 weeks into shorter periods. On each of them, certain changes occur in the body of a woman.
The first trimester lasts approximately from the 1st to the 12th week from the first day of the last menstrual cycle. At this time, the fetus is developing rapidly, its main organs and systems are being formed. The size of the fetus is increasing, but so far only slightly.
The second trimester lasts approximately from the 13th to the 26th week of pregnancy.
The third trimester starts at 27 weeks. By this time, the unborn child is already mature enough to survive outside the womb. The fruit increases significantly in size. By the end of the 3rd trimester, he is ready to be born as a chubby, healthy baby.