In plain words
The myometrium is the thick muscle layer of the uterus. It is the part that squeezes during labor and pushes the baby out. After birth, it keeps squeezing to shrink the uterus back toward its usual size. That squeezing causes afterpains, the cramps many people feel while nursing. The myometrium also stretches through pregnancy as the uterus grows. are irregular squeezes of this same muscle. Some cramping in the first days after birth is expected. Tell your provider if cramps become severe, or if they come with heavy bleeding, fever, or a foul smell.
The deeper version
The myometrium is the smooth muscle layer of the uterine wall. It hypertrophies and stretches during pregnancy and contracts in labor under and stimulation. Postpartum depends on sustained myometrial contraction and , which compress spiral arteries and limit bleeding. Afterpains intensify with breastfeeding because suckling releases oxytocin. Braxton Hicks contractions are spontaneous, irregular, low-amplitude myometrial activity that does not produce progressive cervical change. Cunningham and colleagues (Williams Obstetrics, 26th edition, 2022) cover its physiology in detail. The main clinical question is when myometrial dysfunction, such as , needs intervention rather than observation.
Where it comes up
- Afterpains: cramping while nursingPostpartum: Your Body
- Braxton Hicks and practice contractionsPregnancy: Your Body
- Postpartum bleeding (lochia): what's normal, what's notPostpartum: Your Body
- Heavy bleeding after birth (hemorrhage)Birth and the First Days
What mothers here say about myometrium
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Sources
- Cunningham FG and colleagues — Williams Obstetrics, 26th edition (2022)