How Long Does the Uterus Take to Shrink After Birth?

How long does it take for the uterus to shrink after birth?

Most of the shrinking happens in the first six to eight weeks, and it is fastest at the start. A 2017 Brazilian ultrasound study describes the time needed for the genital organs to involute (return to their non-pregnant state) and for periods to return as usually about 6 weeks. When researchers in Uppsala, Sweden, measured the womb with 3D ultrasound in 50 women after uncomplicated births, it was still getting smaller at eight weeks.

This page is about the womb itself. For the cramping and what helps, see afterpains and postpartum cramping; for every other change, see your body after birth.

Uterus size after birth, from day 1 to week 8

The Uppsala study, published in Acta Obstetricia et Gynecologica Scandinavica in 2012, gives median volumes for the body of the womb and the cavity inside it.

On those medians, the womb had lost about two thirds of its volume by two weeks and about nine tenths by eight weeks (our calculation from the published figures). An earlier Uppsala study of 42 women after vaginal births found the same shape: the maximum front-to-back depth of the womb fell from 92.0 mm on day 1 to 38.9 mm on day 56.

What makes the womb shrink

Contractions. Australia's Pregnancy, Birth and Baby service says that after a vaginal or caesarean birth your uterus continues to have contractions, which feel a little like period pain, and "these contractions help the uterus to reduce in size". Those are afterpains.

The same contractions also help control bleeding. ACOG, the American College of Obstetricians and Gynecologists, explains that the most common cause of postpartum haemorrhage is uterine atony, when the muscles of the uterus do not contract normally: without normal contractions, blood vessels do not tighten after delivery. That is why heavy bleeding after birth is treated as a sign that the womb may not be contracting as it should.

Does breastfeeding make your uterus shrink faster?

Breastfeeding definitely makes it contract. The NHS says that bleeding may be redder and heavier when you breastfeed "because breastfeeding makes your womb contract", that you may feel cramps similar to period pains, and that breastfeeding helps your shape return for the same reason.

Whether it changes how quickly the womb reaches its final size is less certain. The 2001 Uppsala study found no correlation between involution and breastfeeding. The 2017 Brazilian study found a relationship in the first week, but its authors say there is no consensus in the literature and list several studies that found uterine volume independent of breastfeeding. If you are formula feeding, nothing in this evidence suggests your womb will not go back.

Is it different after a caesarean?

Not much in the first week. In the 2017 study, vaginal and caesarean births gave similar uterine volumes, with the only significant difference on day 2, when the womb was smaller after a caesarean. Contractions and afterpains happen after both. For the wound, see C-section recovery week by week.

Why your tummy still looks pregnant

Because the womb is only part of it. The NHS says your tummy "will probably still be a lot bigger than before pregnancy. This is partly because your muscles have stretched." With a balanced diet and some exercise, it says, your shape should gradually return. If there is a gap down the middle of your stomach, see diastasis recti.

How shrinking is checked, and what a scan may show

In the UK, NICE guideline NG194 asks midwives to assess at each postnatal contact, among other things, symptoms and signs of infection, pain, and vaginal discharge and bleeding. At 6 to 8 weeks, NICE says a GP should carry out an assessment and respond to any concerns. In Australia, Pregnancy, Birth and Baby says your tummy will be felt at the 6-week check "to check that your uterus has gone back to its correct position in your pelvis". See the six-week postnatal check.

If you have a scan in the first weeks, some material inside the womb is common. In the 2012 Uppsala study, intrauterine content was seen in 36% of women on day 1, 95% on day 7, 87% on day 14 and 28% on day 28, all after uncomplicated births. The 2001 study called fluid and debris in the cavity "a common and insignificant finding of the involuting uterus". Whether anything needs treating depends on your symptoms and your clinician's assessment.

Signs your womb is not recovering as it should

NICE tells midwives to inform women at the first postnatal contact that sudden or very heavy bleeding, or bleeding that persists or increases, "could indicate retained placental tissue or endometritis", an infection of the womb lining. ACOG adds the detail:

• Heavy bleeding. ACOG defines postpartum haemorrhage as soaking through two pads an hour for more than 1 to 2 hours. It usually happens within 24 hours of delivery but can occur up to 12 weeks later, sometimes because small pieces of placenta stay attached to the uterus. See postpartum haemorrhage and postpartum bleeding.
• Infection. ACOG says endometritis usually happens 2 to 10 days after delivery but can develop up to 6 weeks after. Its signs are fever and chills, feeling tired or sick, abdominal pain or tenderness, and foul-smelling vaginal discharge.

When to call

Contact your midwife, health visitor, GP or maternity unit straight away if:

• bleeding is sudden or very heavy, or it increases rather than settling
• you pass clots, placental tissue or membranes
• you have tummy, pelvic or perineal pain, a fever or shivering, or bleeding or discharge with an unpleasant smell

The NHS lists sudden or very heavy blood loss, possibly with feeling faint or a rapid heartbeat, as a possible postpartum haemorrhage. If you cannot reach your care team, or you feel you need immediate care, call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, or 111 in New Zealand) or go to hospital, as ACOG advises.

Frequently asked questions

How do I know my uterus is shrinking?

Mostly by how things change: afterpains during feeds, and bleeding that gradually turns brownish and decreases until it stops, as the NHS describes. Your midwife asks about bleeding and pain at each contact. Bleeding that gets heavier rather than lighter, or pain that worsens, is the sign to call.

Can you help your uterus shrink faster?

None of the sources on this page recommends a product or technique to speed it up. Breastfeeding makes the womb contract, according to the NHS, though ultrasound studies disagree on whether it changes the end result. For your tummy as a whole, the NHS suggests a balanced diet and some exercise.

Why does my uterus hurt after birth?

Because it is contracting to shrink. Pregnancy, Birth and Baby says these contractions feel a little like period pain, are known as afterbirth pains, and may be felt during breastfeeding. They are normal. Pain that is constant, severe or getting worse, or comes with a fever, is not, and needs checking. Afterpains covers what helps.

Where is the uterus after birth?

By the 6-week check it should be back in your pelvis: in Australia, Pregnancy, Birth and Baby says your tummy is felt then to check your uterus has gone back to its correct position. In the 2001 Uppsala study, the uterus was most often tilted backwards (retroverted) in the early weeks after uncomplicated births.

What size is the uterus after birth?

In the 2012 Uppsala 3D ultrasound study, the median volume of the body of the womb was 756 cm³ on day 1, 253 cm³ at two weeks, 125 cm³ at four weeks and 68 cm³ at eight weeks. A second Uppsala study measured its depth falling from 92.0 mm to 38.9 mm over the same eight weeks.