The Uterus: Function and Anatomy

Definition: The uterus, also known as the womb, is the hollow organ in the female reproductive system that holds a fetus during pregnancy.

The uterus performs multiple functions and plays a major role in fertility and childbearing. This organ is able to change in shape, as muscles tighten and relax to make it possible to carry a fetus.  During pregnancy, the uterus grows and the muscles become stretched and thinner, like a balloon.  Without this ability to expand, the human body would be unable to tolerate the rapid growth of a fetus.

The uterus is a hollow organ made up of three layers of tissue:  

The Perimetrium: This is the outside layer of tissue that lines the outside of the uterus.  

The Myometrium: The middle layer of the uterus is primarily made up of smooth muscle.  

The Endometrium: The inside layer of the uterus that is the layer that builds up over the course of a month and is shed each month if no pregnancy occurs. This shedding of the lining of the uterus is the menstrual period. 

When pregnancy occurs, the endometrium supplies nutrients to the fertilized egg, and eventually supports the placenta.  The muscular nature of the uterus allows it to expand to accommodate a growing fetus.  During childbirth muscular contractions in the uterus help to push the baby out of the body.

During childbirth, the uterus contracts to help push the fetus from the body.  These contractions squeeze the fetus out of the uterus and into the vagina with a series of muscular movements.  After the baby is born, the uterus continues to contract, which helps the organ to return to its normal size and also assists in stopping bleeding that occurs in the uterus during the delivery.

A hysterectomy is a surgery to remove the uterus and is typically performed when the uterus is diseased (such as cancer) or when dysfunctional uterine bleeding (heavy periods, long periods that cause anemia) is unable to be treated using less invasive methods.

A C-section is a surgery to remove a fetus from the uterus rather than delivering in the traditional way through the vagina. 

Pronunciation: YOU-ter-us

Also Known As: womb,

Examples: During pregnancy, the uterus expands to many times its original size and returns to its normal size after childbirth.