Final answer:
Throughout three trimesters of gestation, key developments include organ establishment, bone and muscle growth, and significant increases in the fetus's size and weight. Labor then follows in three stages: cervical dilation, delivery of the baby, and expulsion of the placenta.
Step-by-step explanation:
Major Developments During Each Trimester of Human Gestation
he major developments during human gestation span three key trimesters over a period of 38 weeks. In the first trimester, the embryo undergoes rapid cell division, establishing the foundation of vital organs, the spinal cord, and the beginnings of the nervous system. The second trimester is characterized by significant growth, where structures such as bones and muscles further develop, and the fetus begins to move and react to stimuli.
During the third trimester, there is substantial growth in fetal length and weight, and the bones of the fetus complete their development. The brain continues to mature, body fat increases, and the fetus's previously wrinkled skin smooths out as layers of subcutaneous fat are deposited in preparation for birth. By the 38th week, the fetus generally reaches full term, measuring anywhere from 36 to 51 centimeters in length and weighing between 2.7 and 4.6 kilograms
Stages of Labor
Labor and delivery consist of three stages. The first stage involves the dilation of the cervix, culminating in full dilation at 10 centimeters. The second stage includes the descent and eventual delivery of the baby, while the third stage covers the delivery of the placenta, marking the end of the birthing process.