Final answer:
The first trimester involves placenta formation and nutrient transfer. The second trimester is a period of rapid fetal growth and development. The third trimester is characterized by further fetal growth and symptoms for the mother.
Step-by-step explanation:
The gestation period is divided into three trimesters. The first trimester is characterized by the formation of the placenta and the transfer of nutrients and waste between the mother and the embryo/fetus. During the second trimester, the fetus grows and develops rapidly, and the mother may feel its movements. The third trimester is marked by further growth of the fetus, leading to symptoms such as back pain and swelling for the mother.