Fetal development occurs over trimesters of pregnancy. two three five seven

Answer – Three Trimesters
 The development a fetus occurs over three trimesters of pregnancy. The nine months gestational period in humans is divided into three stages of equal length; the first three months form the first trimester, the fourth to sixth months form the second trimester, and the seventh to ninth month form the third trimester.

Warm up, exercise, cool down