Traditional terms used in medicine which divide the 9-month period of normal pregnancy in women into three stages, each lasting 3 months. The differentiation of cells and tissues in the embryo take place during the first trimester. The mother feels fetal movements early in the second trimester, and there is a rapid growth and maturation of the organ systems. During the third trimester the organ systems are completed, and fat accumulates under the skin of the fetus. It moves into position for birth which brings the third trimester to an end.
Subjects: Genetics and Genomics.