The uterus is a hollow, muscle walled organ that is approximately 7.5 cm in length, 5 cm in breadth, 2.5 cm in thickness, weighing 30 to 40 grams in an adult woman (Gray’s Anatomy, 2013). This reproductive organ is placed within the pelvic cavity. Should a fertilized ovum be implanted into the endometrium, a cascade of anatomical and physiological changes takes place.
The uterus becomes enormously enlarged during pregnancy. This organ undergoes the most significant changes among all other internal organs of the woman’s body (Eden, 2013). Normally, the uterus cannot be palpated because it does not go beyond the pelvis, but by the fourth month, it would grow up for the fundus (the upper part) to reach the abdomen. At the end of the full term pregnancy, it reaches the epigastrium.
By the time of full term, the uterus increases 20 times its original weight and 1,000 times its original volume. The mass increases from 50-70 gm to 1,000 gm and the capacity increases from 10 ml to 5 L (Ile, 2013). Actually, this growth goes on until the 20th week and after that point it does not get heavier. The increase in mass and the size is due to proliferation of the existing muscles as well as development of the new fibers. After the 20th week of gestation, it only stretches to accommodate the baby’s progress. The increase in mass and capacity makes the entire abdominal cavity adapt. Thus, the tissues of anterior abdominal wall stretch and it expands provoking development of the stretch marks (the striae).
During pregnancy, the amount of vessels and nerves increase in the uterus. The shape of the uterus changes during pregnancy. In an adult woman, it is pyriform in shape. By the second month, its shape is more oval. In midgestation, the uterus resembles a round. At the end of full term pregnancy, the uterus becomes elongated again.