The uterus, also called the womb, is an inverted pear-shaped muscular organ of the female reproductive system located between the bladder and the rectum. Its function is to nourish and house a fertilized egg until the fetus, or offspring is ready to be delivered. The uterus is 2.4 to 3.1 inches long, and its wall thickness is approximately 0.8 to 1.2 inches. Lining the uterine cavity is a moist mucous membrane known as the endometrium.

Source: Britannica