Uterus Involution

What is uterus involution?

Uterus involution is the process of your uterus returning to the way it was before pregnancy. It shrinks back down to its nonpregnant size and weight. This process starts soon after childbirth and continues over six weeks. It happens alongside postpartum bleeding and discharge (lochia).

Your uterus increases significantly in size over several months to support your pregnancy. So, it’s important to remember that it takes time for your uterus to return to how it was before. Uterus involution is one part of the postpartum healing process.

What is the purpose of uterus involution?

Involution allows your uterus to return to how it was before pregnancy.

During pregnancy, your uterus grows several times its normal size. It also builds up extra blood and tissue. These changes transform your uterus into a space of nourishment and protection for a growing fetus. Once your baby is born, your body no longer needs that extra space or tissue.

Involution, in part, eventually allows your body to return to a menstrual cycle.

What is the process of uterine involution?

Involution begins as soon as you deliver the placenta (the third stage of labor). Your uterus will start contracting again. The contractions decrease blood flow to the area where the placenta was attached to your uterus. This is your body’s way of minimizing bleeding. It’s essential to prevent excessive bleeding (postpartum hemorrhage).

The contractions also help your uterus shrink back to its prepregnant size and shed extra tissue (lochia). During the first 12 hours postpartum, uterine contractions are regular and strong. As this happens, you may experience cramps (afterpains).

Afterpains are typically only noticeable for a few days after birth. But you’ll likely feel it most if (and when) you breastfeed or pump breast milk. Afterpains also tend to be more painful if you’ve given birth before.

It takes up to six weeks for uterus involution to complete. Your uterus weighs less and takes up less space in your pelvic cavity as each day passes. It may look like you still have a “baby bump” for a little while after childbirth. Even with your baby on the outside, your uterus is still taking up a lot of space in your abdomen.

How does breastfeeding affect uterus involution?

Your uterus will shrink more rapidly if you breastfeed. When your newborn suckles (or you pump), your body makes oxytocin (a hormone). It causes your uterus to contract.

Checking involution progress

During your recovery in the hospital, a healthcare provider will check on the progress of your uterus’s involution. They’ll press on your belly to check your uterus’s fundal height — where the top of your uterus is. They’ll also check to see if your fundus feels firm. Your provider will check your lochia during this time, too.

If your uterus isn’t involuting as expected or is squishy, you’re at increased risk for postpartum hemorrhage. Your provider will likely do a fundal massage to help your uterus contract. They may also give you manufactured oxytocin (Pitocin®) to help stimulate contractions.

How does the uterus change throughout involution?

Uteruses generally decrease in weight and size along a similar timeline. That said, your uterus’s size and weight before pregnancy depend on various factors, like:

• Whether you’ve given birth before (most women have a slightly larger uterus after previously giving birth)
• If you had multiples (like twins or triplets)
• How far along in your pregnancy you delivered

In general, here’s a breakdown of how much a uterus weighs after birth:

• Right after delivery: 1,000 grams (about 2 pounds)
• One week: 500 grams
• Two weeks: 300 grams
• Four weeks: 100 grams
• Eight weeks: 60 grams (about 2 ounces)

Your uterus shrinks during involution, from roughly the size of a grapefruit that fills your entire pelvic cavity to the size of a pear. Here’s the timeline of how your uterus descends (lowers) back into your pelvis:

• At about an hour after childbirth, the top of your uterus (fundus) should be around your belly button.
• After that, the fundus should steadily get lower in your abdomen by 1 centimeter every 24 hours.
• At about one week postpartum, your fundus should be at your pubic bone (symphysis pubis).
• At 10 to 14 days, the fundus should be back in your pelvic cavity.

What issues can happen with uterus involution?

The two main issues that can happen with uterus involution are subinvolution and postpartum hemorrhage.

Subinvolution

Subinvolution means your uterus isn’t decreasing in size as it should. Healthcare providers may also refer to this as “subinvolution of placental sites.” This is delayed closure of the spiral arteries where the placenta was attached to your uterus.

Your provider may suspect subinvolution after a fundal exam. Having lochia rubra (red, bloody discharge) for more than one week postpartum is also a sign of subinvolution. Your provider may recommend an ultrasound to see what’s happening.

Sometimes, your uterus is too tired to continue contracting. Or other issues interfere with the process. Some causes of subinvolution include:

• Uterine infections, like endometritis
• Remaining debris in the uterus, like fragments of the placenta
• Prolonged labor or prolonged exposure to oxytocin (Pitocin) to help your uterus contract
• Cesarean (C-section) delivery
• Receiving general anesthesia (like for an emergency C-section)

Postpartum hemorrhage

Postpartum hemorrhage (PPH) is excessive uterine bleeding after childbirth. It can be life-threatening.

About 80% of PPH cases happen because uterine contractions aren’t strong enough after birth. PPH usually occurs within 24 hours of childbirth. But it can happen up to 12 weeks after delivery.

While you’re recovering in the hospital, your healthcare team will check on you frequently to monitor your bleeding (lochia). If you hemorrhage, they’ll act quickly to treat it.

If you have excessive bleeding at home, get to the nearest ER as soon as possible.

How do I take care of myself?

During postpartum, it’s important to rest and take care of yourself — not just your baby. Lean on loved ones to help with your baby so you have time for self-care.

Afterpains from uterus involution can be intense, especially during breastfeeding. You may feel intense cramping lasting about five minutes and then gradually easing. Some ways to manage afterpains include:

• Breathing and relaxation exercises (like the ones that help with labor pains)
• Lying on your stomach with a pillow under your lower belly
• Taking an over-the-counter pain reliever that your healthcare provider recommends (ibuprofen may work better than acetaminophen)
• Walking