What is the uturus?

Written by Dr. Specialist Stine Andreassen
Specialist in Gynecology and Obstetrics, PhD in Obstetrics in 2015 and more than 15 years of clinical practice in Obstetrics and Gynecology

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The uterus, sometimes called the womb, is a hollow muscular organ where a pregnancy develops. It is one of the central organs of the female reproductive system and plays an important role in menstruation, fertility, and pregnancy.

Where is the uterus located?

The uterus sits in the pelvis between the bladder and the rectum. In most women, it is approximately the size and shape of an upside-down pear, although size and position vary.

What does the uterus do?

• Menstruation: Each month the lining of the uterus thickens in preparation for a possible pregnancy. If pregnancy does not occur, this lining sheds during menstruation.

• Pregnancy: If a fertilized egg implants into the uterine lining, the uterus provides protection and nourishment throughout pregnancy.

• Labour and birth: During labour, powerful contractions help move the baby through the birth canal.

What is the endometrium?

The endometrium is the inner lining of the uterus. This tissue thickens each month in preparation for pregnancy and sheds during menstruation if pregnancy does not occur. Each month, the lining thickens in response to hormonal changes. If a fertilized egg implants, the endometrium provides support and nourishment in early pregnancy. If pregnancy does not occur, the lining sheds and leaves the body during menstruation.

Related resources

• What is fertility?

• What is endometriosis?

• Learn more about menstruation

FAQ – The uturus

• What is the uterus?

  The uterus is a muscular organ where pregnancy develops.

• What is the endometrium?

  The endometrium is the inner lining of the uterus. Each month, the lining thickens in response to hormonal changes. If a fertilized egg implants, the endometrium provides support and nourishment in early pregnancy. If pregnancy does not occur, the lining sheds and leaves the body during menstruation.

• Does the uterus change during pregnancy?

  Yes. The uterus expands significantly to accommodate the growing baby.