Uterine Subinvolution: Causes, Symptoms and Treatment

Your baby’s in your arms, but your womb has still got some work to do. Soon after you’re done giving birth, the uterus begins the process of contracting back down to its pre-pregnancy size. But if the uterus doesn’t contract well, it can result in subinvolution. Let’s go through the facts on this condition, warning signs, and how it’s treated.

What is uterine subinvolution?

woman uterus belly hand
After nine months of housing a growing baby, the uterus has to shrink back down to its pre-pregnancy shape and size. For reference, that means going from a structure that can hold about 10 L volume to one which can hold a teaspoon volume.

This starts with uterine contractions after the birth, and you may feel these contractions as afterbirth pains (postpartum cramps). The worst of the afterbirth pains are usually over within the first day or 2 days after giving birth, but the uterus continues to contract after this. If the process happens too slowly, the uterus remains enlarged. This condition is called subinvolution.

What causes uterine subinvolution?


Retained placental tissue

After giving birth, the placenta naturally comes out of the mother’s body. However, if the placental site doesn’t clear entirely, leftover tissue in the uterus can prevent the uterus from shrinking properly.

Oxytocin levels

You may have heard of oxytocin as the “love hormone”. It’s what makes your heart melt when you look down at your nursing baby, but it’s also what triggers uterine contractions. If you’re not producing enough oxytocin, the contractions may be weak and it can result in uterine subinvolution.

Activity levels

Excessive activity is thought to slow the healing process and put you at risk of uterine subinvolution.

Other risk factors are thought to include macrosomia (a very large baby), polyhydramnios (too much amniotic fluid), or delivering multiples like twins or triplets.

Symptoms of uterine subinvolution

panty liner sanitary napkin

Postpartum bleeding or lochia can be a sign of how the uterine contraction process is progressing. Some lochia bleeding is normal, and will resolve on its own within about a month of delivery. It starts off as heavy like a menstrual period, becoming progressively lighter in color and amount until it’s indistinguishable from normal vaginal discharge.

But if the uterus isn’t contracting properly, you may see:

  • Lochia flow that contains large clots
  • Lochia lasts longer than 4 weeks
  • Irregular bleeding alongside lochia discharge

Subinvolution can also put you at risk of bacterial infections, and the infection may cause fever.

Treatment for uterine subinvolution

medicine painkiller pills

Subinvolution is one of the leading causes of dangerous postpartum hemorrhage, so if you’re showing signs like abnormal lochia bleeding, it’s important to see a doctor to identify the cause.

If an ultrasound scan shows you have retained placenta fragments in there, you may need to be treated with antibiotics and have the tissue removed in hospital. If your case is only mild and you’re not bleeding too heavily, you may be treated as an outpatient and given a course of drugs to promote contractions.

Prevention of uterine subinvolution

It’s not always possible to prevent subinvolution, but there are ways to reduce your risk. It’s important to listen to your body and not push yourself too hard when recovering from birth.

Breastfeeding also releases the oxytocin that triggers uterine contractions, so that’s one more perk you can enjoy if you’re nursing. Go easy on yourself, and give your body the right balance of rest and gentle activity while you recover from birth.

Abnormal lochia? Speak to your doctor about subinvolution of the uterus

doctor hospital medicine

If your uterus is taking longer than usual to return to its usual size after pregnancy, it can put you at risk of some dangerous conditions like infection and hemorrhage. Paying attention to warning signs of subinvolution is important to make sure you’re on the mend.

If you’re concerned about abnormal lochia, don’t hesitate to speak to your doctor or midwife. In the meantime, don’t forget to rest up and ask for help when you need it. The first month of your baby’s life can be a hectic time, but it’s important to give your body the downtime you need to recover.