Belly after birth: what the first weeks change, why the belly stays slack and what a gut scan measures

What your belly looks like after the birth: the first weeks

In this article you read what happens to your belly after birth in the weeks and months that follow: how fast the womb shrinks, why the belly can stay soft, what the studies on belly binding and exercises really measured, and what a gut scan can and cannot say about you. That matters, because the timeline people expect is much shorter than the timeline that has been measured, and because a soft belly and a bloated belly are two different things, two different answers go with them. The BioProfile gut scan gives you an indication of where you stand today on gut symptoms, as one of the 11 areas the full scan assesses. This is not a diagnosis. It is insight, to see where you stand today, and to help you make better choices in your food and your daily routine. What this scan does not do: point to a cause or make a diagnosis. Only a doctor can do that.

In an ultrasound study in Lithuania, 46 women were followed after an uncomplicated vaginal birth, 24 of them giving birth for the first time and 22 who had given birth before, with ultrasounds on days 1, 3, 10, 30, 42 and 60.⁠¹ In the women giving birth for the first time the length of the womb went from 162 +/- 17.5 mm on day 1 to 81 +/- 8.4 mm on day 30 and 63 +/- 8.2 mm on day 60; in the women who had given birth before, from 174 +/- 13.5 mm to 83 +/- 6.7 mm and 71.5 +/- 12.1 mm over the same 60 days. The measurement from front to back went in the same period from 82 +/- 10.1 mm and 94 +/- 13.1 mm to 36 +/- 3.9 mm and 39 +/- 8.0 mm, and the shrinking follows the same pattern in both groups, while it takes longer in women who have given birth before.⁠¹

What this means for you: two months after the birth, your womb is still getting smaller, but the shrinking of the womb alone does not explain how your belly looks. Your skin, the tissue under your skin, weight you are still carrying, how your abdominal wall works, your posture, diastasis and a bloated feeling can all play a part. Thuisarts describes those same weeks from another angle: after the birth you lose blood and clots through the vagina, and this becomes less and stops within 6 weeks.⁠⁵ After a caesarean section, the timeline is set out in the same terms: it takes about 6 weeks before you can do everything again, with no housework in the first 2 weeks, no heavy work in the first 6 weeks and no sport yet in the first 6 weeks.⁠⁶

Why your belly stays slack after birth

If your belly feels soft under your hand in these months, there is a second explanation besides the shrinking womb. The straight abdominal muscles, the rectus abdominis, lie to the left and right of a strip of connective tissue that runs down the middle, the linea alba. When that strip has been stretched wide, the abdominal wall gives way where it used to hold, and that is called diastasis.

A cross-sectional study at the Shanghai East Hospital compared 200 women: 143 in whom an ultrasound found diastasis of the rectus abdominis muscles and 57 as a control group, with births between January 2019 and December 2021 and participants recruited between January 2022 and December 2023.⁠⁷ The measurements were done during the lying-in period, mostly within the first week after the birth, and then after 6 weeks, 3 months and 6 months. The cut-off used was a distance between the rectus abdominis muscles of more than 2 cm, measured 3 cm above the navel, at the navel, or 3 cm below it. In 122 of the 143 women with diastasis (85.31 percent) the linea alba was widened, and the muscle activity of the pelvic floor during a fast contraction was 39.48 microvolts in this group against 43.21 microvolts in the control group (p smaller than 0.05).⁠⁷

In plain words: the slack look is connective tissue that has been stretched wide, and in this study it went together with a weaker fast response of the pelvic floor. How often it happens was measured in a Norwegian study: diastasis was present in 55.2 per cent of the exercise group and 54.5 per cent of the control group 6 weeks after a first birth, in 43.7 and 44.3 per cent after 6 months, and in 41.4 and 39.8 per cent after 12 months.⁠² So one year after a first birth, four in ten women in that study still met the study’s criteria for diastasis.

Your belly is not the only thing that changes. In a Dutch study of 415 women between 6 weeks and 1 year after giving birth, 57.1 per cent (95% CI 52.3 to 61.8) had involuntary urine leakage: 52.0 per cent among women who had given birth for the first time and 61.9 per cent among women who had given birth before. Of the women with involuntary urine leakage, 38 per cent called it bothersome.⁠⁸ So that is more than half, and many people in that group do not see it as a small thing.

Belly binding after birth, and getting your belly firmer

Binding the belly after birth is an old custom that now has numbers behind it. A systematic review with network meta-analysis brought together 27 randomised studies covering 1,340 women after birth who had been diagnosed with diastasis.⁠³ The highest-ranked treatment was a physiotherapy programme that combined abdominal exercises, breathing techniques, education and kinesio taping. In the network analysis, it went together with an estimated greater reduction in the distance between the rectus abdominis muscles of -26.25 mm (95% CI -29.41 to -23.09) compared with no exercise programme, and exercises with electrical muscle stimulation came to -22.62 mm (95% CI -26.58 to -18.67). Individual aids on their own scored much lower: an abdominal binder alone gave -10.32 mm and kinesio tape alone -3.93 mm.⁠³

What this means for you: an abdominal binder can reduce the distance between the rectus abdominis muscles compared with no treatment, but the research does not show that a binder improves the way your belly looks, your strength, pain, your daily functioning or your quality of life. Exercise combined with other techniques seems to work better.

The Norwegian study is the warning on the other side. 175 women after a first birth were randomised, 87 to exercise and 88 to control, with a supervised programme of 16 weeks that started 6 weeks after the birth. The authors’ conclusion: a weekly programme of strength work for the pelvic floor and the abdominal muscles plus daily pelvic floor exercises at home gave no lower prevalence of diastasis than no programme, measured up to 12 months after the birth.⁠² Read together, the two studies say that a targeted programme in women who already have diastasis changes the measured distance, while a general programme offered to everyone after a first birth did not change the numbers with diastasis.

As a foundation under all of this, the Gezondheidsraad says that adults should do at least two and a half hours of moderate-intensity physical activity a week, and that muscle- and bone-strengthening activities are recommended; its advice to the Minister of VWS is to encourage people to keep moving more and sit less.⁠⁹ According to the same page, this lowers the risk of chronic diseases such as diabetes and cardiovascular disease, of depressive symptoms and, in older people, of fractures.⁠⁹ After a caesarean section, the first 6 weeks are the exception to this.⁠⁶ Once your recovery allows it and there are no medical reasons not to, the longer-term goal is to build back gradually to the general advice of at least 150 minutes of moderate-intensity activity a week. When and how quickly you build up to that depends on the birth, how your wound heals, your symptoms, how active you were before and any complications before or during the birth.

The weight that stays, and eating in these months

In a cohort of 461 women at a medical centre in the north of Taiwan, recruited between March 2014 and March 2016, the weight still carried on average compared with the weight from before the child was 4.6 +/- 3.5 kg one month after the birth and 2.1 +/- 3.3 kg after six months.⁠⁴ That is the middle of a wide spread, and it is a number measured over months instead of over weeks.

If you feed your child at the breast, the Voedingscentrum is clear about eating less. Your body needs more energy and nutrients than usual to make milk, and you eat about as much as you did in the months before the birth.⁠¹⁰ Active dieting is advised against, because eating less than you need is not good now that making milk asks extra energy of your body, and a strict diet can leave you short of nutrients.⁠¹⁰ Feeding at the breast can, in some women, help weight come off, and that differs a lot from person to person.⁠¹⁰

What a gut scan measures, and what it does not

A belly that stays round in these months can be a womb that is still shrinking,⁠¹ a linea alba that has been stretched wide,⁠⁷ weight that is still being carried,⁠⁴ or a belly that is bloated from the gut. Those last complaints are what the gut scan asks about: how much you notice of them over the past two weeks, converted into a score and a reading band, so that you have a starting value instead of a memory. What the causes of a bloated belly can be is in a bloated belly and what a gut scan measures.

A questionnaire cannot tell those four apart. A questionnaire does not measure the distance between your rectus abdominis muscles, which needs an ultrasound and a fixed cut-off,⁠⁷ and it points to no cause. It is not a diagnosis.

Thuisarts names the signals to watch for. In the first 10 days after the birth you call the midwife or the gynaecologist, and after 10 days the GP or the out of hours GP service.⁠⁵ Call straight away if you have a fever or a flu like feeling, heavy blood loss from the vagina, a foul smell to the discharge together with fever or belly pain, a growing headache that painkillers do not ease, double vision or flashes of light, pain high in your belly, nausea or vomiting, a swollen face or swollen hands or feet, a thick, red and painful leg, severe anxiety or confusion, or severe low mood.⁠⁵ After a caesarean you call the midwife or the doctor at the hospital if you have a fever above 38.5 degrees, a lot of belly pain, a severe headache, or heavy blood loss again.⁠⁶

In summary

The womb shrinks quickly after birth and is usually almost back to its pre-pregnancy size after four to six weeks, but the way your belly looks can keep changing for months.⁠¹ Behind a slack or pudding belly after birth there is often a widened linea alba, present in about 55 per cent of women 6 weeks after a first birth and in about 40 per cent after 12 months.⁠² A network meta-analysis estimated a 10.32 mm greater reduction in the distance between the rectus abdominis muscles with an abdominal binder than without specific treatment. A separate programme of exercises, breathing, education and kinesio taping had a larger estimated reduction, but it did not include an abdominal binder,⁠³ and the weight still carried on average was 2.1 +/- 3.3 kg after six months.⁠⁴ A gut scan gives you a baseline for gut symptoms such as a bloated belly and is not a diagnosis. The warning signs above belong with the midwife, the gynaecologist or the GP.⁠⁵