Uterus: definition and meaning
The uterus, also called the womb, is a hollow, muscular, pear-shaped organ in the pelvis where a fertilized egg implants and a pregnancy grows. Each menstrual cycle its inner lining, the endometrium, thickens to prepare for pregnancy and then sheds as a period if no pregnancy happens. Its muscle contractions cause period cramps.
Parts of the uterus
| Part | What it is |
|---|---|
| Fundus | the rounded top, between the openings of the fallopian tubes |
| Body (corpus) | the main part, where an embryo usually implants |
| Cervix | the narrow lower end that opens into the vagina; see cervix |
| Endometrium | the inner lining that builds and sheds; see endometrium |
| Myometrium | the thick muscle layer that contracts during periods and labor |
How the uterus changes across the cycle
After your period, rising estrogen rebuilds the lining. After ovulation, progesterone makes it soft and nourishing. If no embryo implants, hormones fall, the lining breaks down and the muscle contracts to push it out, helped by prostaglandins. That is your period, and those contractions are cramps.
Common conditions of the uterus
- Fibroids: non-cancerous growths in the muscle, which can cause heavy periods.
- Adenomyosis: lining tissue grows into the muscle wall, causing painful, heavy periods.
- Polyps: small growths of the lining that can cause bleeding between periods.
- A tilted (retroverted) uterus: a normal variation in about 1 in 4 people.
See a doctor if your periods are very heavy, very painful, or you bleed between periods or after sex. These are common and often treatable, but they deserve a proper look.
Frequently asked questions
How big is the uterus?
About 7 to 8 cm long, roughly the size of a small pear, when not pregnant. It can stretch to hold a full-term baby.
Does the uterus affect mood?
Not directly. Mood changes across the cycle come mainly from hormone shifts in the brain, though pain from the uterus, like strong cramps, can certainly affect how you feel.
Sources
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
Endometrium: definition and meaningThe endometrium is the inner lining of the uterus that thickens each cycle and sheds as your period. How it changes by phase and what thickness means.
What is the cervix?The cervix is the narrow lower end of the uterus that opens into the vagina. What it does in your cycle, in pregnancy, and why screening matters.
Uterine fibroids: definition and meaningUterine fibroids are noncancerous growths of muscle in or on the uterus. What they are, how they affect periods and mood, and when to see a doctor.Period cramps: why they happen and what actually helpsPeriod cramps explained kindly: why your uterus cramps, how long it lasts, what really helps (timing matters) and the signs that need a doctor.The 4 phases of the menstrual cycle, in colorThe 4 phases of the menstrual cycle explained simply: what your hormones do in each, how long each lasts, and how mood and energy usually change.