Uterus involution is a natural process that involves your pregnant uterus returning to its pre-pregnancy state. The process begins after you deliver your baby and the placenta and takes about six weeks to complete. You may experience postpartum cramps called afterpains during uterine involution.
Uterus involution refers to the process where your pregnant uterus (womb) returns to the way it was before pregnancy. Your uterus goes through major changes when you’re pregnant. The lining of your uterus thickens, your blood vessels widen and your uterus grows several times its normal size. These changes transform your uterus into a space of nourishment and protection for a growing fetus.
Once you no longer need these changes to support your pregnancy, your uterus returns to its pre-pregnancy state.
Uterine involution is a significant post-pregnancy change that allows you to regain some comfort and fertility. Your uterus shrinks during involution, lessening the pregnancy weight your body has to carry. In addition, involution is necessary for you to begin menstruating. Instead of supporting a fetus, your uterus goes through changes that allow you to become pregnant again.
Involution begins as soon as the placenta is delivered. The placenta is the organ that allows the mother, or gestational parent, to share nutrients with a fetus. It’s attached to your uterus during pregnancy. The placenta is delivered shortly after your baby is born.
During uterine involution, your uterus returns to the condition and (approximate) size that it was before pregnancy. After your provider delivers your baby, your uterus contracts to deliver the placenta. The repeated squeezing and relaxing in your uterus muscle wall compresses the blood vessels. The narrowed blood vessels prevent you from losing too much blood at the site where the placenta was once attached to your uterus (postpartum hemorrhage).
Over the next several hours and days, your uterus continues to contract and decrease in size. It weighs less and takes up less space in your pelvic cavity as each day passes.
The lining of your uterus (endometrium) regenerates, or builds back up, too.
Uteruses generally decrease in weight along a similar timeline. That said, your uterus’s size and weight before pregnancy depend on various factors, including whether or not you’ve given birth before. Generally, people who’ve had a baby previously will have slightly larger uteruses than people delivering their first child.
The following breakdown offers an approximation of how much a uterus weighs soon after you’ve had your baby up until eight weeks.
Your uterus shrinks during involution, from roughly the size of a grapefruit that fills your entire pelvic cavity to the size of a pear.
It takes about six weeks for your uterus to return to its pre-pregnancy weight and size.
Your uterus will shrink more rapidly if you breastfeed. When your newborn suckles, your body produces a hormone called oxytocin that causes your uterus to contract. The increased contractions narrow the blood vessels in your uterus, preventing bleeding. The contractions also cause your uterus to shrink back to its original size more quickly.
You may experience pain from uterine contractions, called afterpains, and notice a discharge called lochia in the weeks following delivery. Both are normal signs of uterine involution.
You may experience afterpains for a few days after having your baby, especially if this isn’t the first time you’ve given birth. As your uterus continues to contract, you may experience what feels like mild labor pains or menstrual cramps. The pain often intensifies when you’re breastfeeding your newborn. Afterpains usually become much milder and easier to manage by the third day after you’ve had your baby.
Vaginal discharge called lochia is normal after childbirth. Lochia consists of materials from your uterus that your body sheds after childbirth, including portions of your uterine lining, blood cells and bacteria. Lochia may smell musty or stale, similar to menstrual discharge. Its appearance will change as you get further away from your delivery date.
It’s common to have a lochia discharge from four to six weeks after you’ve delivered your baby. You’ll likely have less lochia if you had a c-section instead of a vaginal delivery.
During your postpartum checkup, your provider will check to see that your uterus is returning to its pre-pregnancy size. If your uterus isn’t decreasing in size as it should (a condition called subinvolution), your healthcare provider may order an ultrasound to see what’s happening. A uterus that is slow to involute is often the result of an infection or remaining debris in the uterus, like fragments of the placenta.
Wearing pads can help manage the lochia. Avoid using tampons or inserting anything inside your vagina until six weeks after having your baby or until your provider says it’s safe.
Afterpains can be intense, especially during breastfeeding. You may feel intense cramping lasting about five minutes and then gradually eases. To manage afterpains:
Cramping and discharge are normal after you’ve had your baby, but excessive bleeding or signs of infection require medical attention. See your provider if you notice any of the following:
A note from Cleveland Clinic
Your body changes rapidly to adjust to pregnancy. Similarly, your body rapidly reverts to its pre-pregnancy state. Consider that your uterus loses half of its pregnancy weight just one week after you’ve had your baby. You may notice unpleasant side effects in the meantime, like afterpains. Remember that mild cramping a few days after delivery is a good thing. It means that your body is returning to its new normal. Pain medications, heating pads and light exercise can help ease the discomfort as your uterus gets smaller.
Last reviewed by a Cleveland Clinic medical professional on 04/01/2022.
Learn more about our editorial process.