The womb, also known as the uterus, is a hollow, muscular structure within the female reproductive system. Its primary function involves supporting the development of a fertilized egg into a fetus until birth, while also being responsible for the monthly menstrual cycle when pregnancy does not occur. This organ is hormone-responsive, meaning its activities are largely controlled by female hormones.
Where is the Womb and What Does it Look Like?
The womb is located in the female pelvis, positioned between the bladder and the rectum. It is supported by various ligaments and pelvic floor muscles. This organ is often described as pear-shaped.
In a non-pregnant adult, the womb measures about 7.5 to 8 centimeters (about 3 inches) in length, 5 centimeters (about 2 inches) wide, and 3 to 4 centimeters (about 1.5 inches) thick. Its average weight is approximately 60 grams. The upper, rounded part of the womb is called the fundus, and it connects to the fallopian tubes. The lower, narrow part, known as the cervix, extends into the vagina. The womb’s wall has three layers: the inner lining called the endometrium, the thick middle muscular layer known as the myometrium, and an outer covering called the perimetrium or serosa.
The Womb’s Central Role in Pregnancy
The womb provides a nurturing environment for a developing fetus during pregnancy. If an egg is fertilized, it travels to the womb and implants into its inner lining, the endometrium. This implantation marks the beginning of a pregnancy.
The endometrium undergoes changes to prepare for and support a pregnancy. It thickens and becomes rich with blood vessels and glands, forming a receptive environment for the embryo. This specialized lining helps to nourish the early embryo and, as pregnancy progresses, contributes to the formation of the placenta, which delivers oxygen and nutrients to the fetus. The muscular myometrium layer also expands to accommodate the growing baby. During childbirth, these muscles contract to push the baby through the birth canal.
The Womb When Not Pregnant
When not pregnant, the womb remains active as part of the menstrual cycle. Each month, hormones cause the endometrium to thicken in preparation for pregnancy. Blood vessels and glands in this lining grow, creating a suitable environment.
If fertilization does not occur, hormone levels decrease. This signals the womb to shed its thickened endometrial lining. This shedding process is known as menstruation, and involves the discharge of blood and tissue through the vagina. After menstruation, the endometrium regrows, starting a new cycle in anticipation of another pregnancy.