Abdominal exercises, including curl-ups, are generally safe after birth for women with diastasis recti. In a 2023 randomized trial, 12 weeks of curl-ups made women with diastasis stronger without widening the gap or worsening pelvic floor symptoms. How your core functions matters more than a finger measurement, so a pelvic floor assessment is the best place to start.

When I was treating pelvic floor clients, one moment came up again and again. A new mom would roll from lying on her back up to sitting, look down, and see a ridge rise along the middle of her belly. She'd freeze. Then someone would press their fingers in above her belly button and count.

The rule we followed, and the one I taught, was simple. If you could sink more than three fingers in horizontally, you backed off all abdominal work until the tone came back and the separation closed. I said some version of that to a lot of women, and I believed it was the right call.

The research has moved a long way since then. What I'd tell a client today is different, and the reasons are worth knowing if you've been sitting out ab work since someone measured your belly.

What Diastasis Recti Is, and How Common It Is After Birth

Diagram of diastasis recti showing the gap between the abdominal muscles after pregnancy

The linea alba is the band of connective tissue between the two sides of your six-pack muscle. During pregnancy it stretches wider to make room for your baby, and it's usually widest around the belly button. Illustration by Body Co Health & Wellness, not to scale.

Diastasis recti is a widening of the connective tissue (the linea alba) between the two sides of your six-pack muscle. Your belly has to make room for a growing baby, and this is one of the ways it does that.

It's close to universal. In an ultrasound study of 84 first-time moms, every single woman had a diastasis at 35 weeks of pregnancy. By six months after birth, 39% still did, which means most had resolved on their own.

A larger Norwegian group of 300 first-time moms, measured by finger widths, found that about a third (32.6%) still had a diastasis at 12 months postpartum, according to the 12-month Norwegian cohort. Those women didn't report more back or pelvic pain than women without one. So a diastasis that's still there months later is common, and it's also something you can build strength around.

The Advice We Used to Give, and Why It Made Sense

Nurse in gloves and patient smile while sitting in a hospital bed in a bright room by a window.

The old approach came from a reasonable place. We could see and feel the gap, and we assumed that anything loading the front of the belly, especially a crunch, would pull it further apart. Protecting the tissue until it closed felt like the careful thing to do.

That advice matched the guidance of the time, and our own blog reflected it. Back in 2018 and 2019, our posts advised against crunches for women with diastasis. The trials that changed our thinking, which followed women through months of ab training, hadn't been published yet.

What a Crunch Does to the Gap

Illustration of the diastasis recti gap narrowing during a crunch on ultrasound

When researchers put an ultrasound on the belly during the exercises we were most worried about, the results surprised a lot of us. In the crunch ultrasound study, 84 first-time moms were measured in late pregnancy and at three points in the first six months after birth. A crunch brought the two sides of the muscle closer together while they did it, every time.

The drawing-in exercise, pulling the belly button toward the spine, which many of us taught as the safe alternative, tended to widen the gap slightly in that moment. That study looked at what happens during the exercise, not over months of training. Still, it was one of the first signs that our rule had the risk pointing the wrong way.

Twelve Weeks of Curl-Ups: The 2023 Trial

Chart showing diastasis recti exercises postpartum improved ab strength without widening the gap

The study that changed my thinking most was a randomized trial published in 2023. Seventy women who had diastasis 6 to 12 months after giving birth were split into two groups. One group did curl-ups and head lifts at home for 12 weeks. The other group was told to avoid abdominal exercise, which is close to the advice I used to give.

After 12 weeks, the difference in gap width between the two groups was about 1 mm. The curl-up group's abdominal strength improved, and pelvic floor symptoms and pain didn't get worse.

Curl-ups made women with diastasis stronger after birth, and the gap stayed where it was.

Why the Gap Number Matters Less Than We Thought

Research findings on diastasis recti and pelvic floor symptoms postpartum

For years, the finger measurement drove almost every decision. Newer research suggests it tells us less than we assumed about how a woman will feel.

In the symptoms study, women with diastasis didn't have more leaking, prolapse, low back pain or pelvic girdle pain than women without it. They did tend to have weaker abs and more abdominal pain, and strength is something training can change.

Exercise doesn't reliably close the gap, though. A review of 16 trials including 698 postnatal women found abdominal exercise had only a small effect on gap width, too small to matter clinically. So when we say curl-ups don't make diastasis worse, we're not promising they'll make it disappear. What they can do is help you get stronger and more comfortable in your body.

Clients often ask about the dome or ridge they see when they sit up. There isn't research yet showing that a dome causes harm, or that it doesn't, so our pelvic health team looks at it as part of an assessment rather than treating it as an automatic stop sign.

What I'd Tell a Client Today

Trainer kneels beside woman during therapy, while another person sits on a stability ball in a studio.

If you came to me today with a diastasis three fingers wide and a list of exercises you'd been told to avoid, I'd start by telling you that the measurement is one piece of information. It doesn't decide what your body can do.

Ab work, including curl-ups, can be part of rebuilding after birth. What guides how fast you progress is how you feel. Pain, leaking or a heavy, dragging feeling in your pelvis are reasons to adjust and get assessed, whatever your gap measures.

Canada's guidance has caught up with this for the postpartum year. The 2025 Canadian postpartum guideline encourages pelvic floor and gentle abdominal training as soon as you feel able, and it names fear of movement, including fear about diastasis, as a barrier worth screening for.

What our pelvic health team sees today is that many women have been holding back far longer than they needed to. Once they have a plan built around how their core works, rather than a number, they get stronger and start to trust their body again.

If You're Pregnant: Where the Guideline and the Research Stand

Two women in black outfits doing front plank on a rug, smiling in a bright studio.

Pregnancy is a separate question, and right now the official guidance and the newer research don't say the same thing.

Canada's current pregnancy guideline is the 2019 Canadian Guideline for Physical Activity throughout Pregnancy. It recommends that all pregnant women without contraindications stay active, with at least 150 minutes of moderate activity a week. For women with a visible diastasis, it advises seeking physiotherapy advice and avoiding abdominal strengthening exercises such as curls, because they may worsen the condition. The 2025 guideline covers the year after birth, and the 2019 guideline remains the current one for pregnancy.

Two randomized trials have been published since then. In a 2024 Norwegian trial, 96 pregnant women who already had diastasis at 24 weeks did 12 weeks of abdominal and pelvic floor exercises or no program. The exercises had a negligible effect on the gap, both right after the program and at six weeks postpartum. In a 2025 Brazilian trial, 63 first-time pregnant women at 18 to 21 weeks were split between general exercise, general exercise plus deep core work, and general exercise plus crunch-type ab work. Neither targeted program substantially changed the gap or pelvic floor symptoms compared with general exercise.

One more detail from the Norwegian trial helps here. The gap widened in both groups through pregnancy and was smallest for both at six weeks after birth. During pregnancy, that widening is expected, because your belly is making room.

Because the guideline and the research don't line up yet, the best next step is a conversation with your pelvic health physiotherapist and your prenatal care provider about what fits your pregnancy.

Book a Pelvic Floor Assessment

Therapist helps a woman lying on a bed as she adjusts a draped cover during a body treatment session

If you've been avoiding ab work since someone measured your belly, a pelvic floor assessment will show you where your core and pelvic floor are today and give you a plan to rebuild from there.

Book a pelvic floor assessment →

Frequently Asked Questions

Can you do crunches with diastasis recti?

After birth, research suggests you can. In a 2023 randomized trial, women with diastasis who did curl-ups for 12 weeks got stronger abs without widening the gap or worsening pelvic floor symptoms. A pelvic health physiotherapist can help you decide where to start.

How many fingers wide is a diastasis recti?

There's no single agreed cut-off. Some studies count two or more finger widths as diastasis, while ultrasound studies use measurements in millimetres. A finger measurement on its own doesn't predict symptoms or tell you which exercises are safe.

Does diastasis recti go away on its own after birth?

For many women it improves without treatment. In one ultrasound study, every first-time mom had diastasis at 35 weeks of pregnancy, and 39% still did six months after birth. In a Norwegian study of 300 first-time moms, about a third still had it at 12 months.

Does diastasis recti cause back pain or leaking?

Research hasn't found that link. Women with diastasis in a 2021 study didn't have more leaking, prolapse, low back pain or pelvic girdle pain than women without it, though they did tend to have weaker abs and more abdominal pain.

Is it safe to do ab exercises with diastasis recti during pregnancy?

Canada's 2019 pregnancy guideline advises avoiding abdominal strengthening such as curls when diastasis is visible. Two randomized trials published in 2024 and 2025 found that abdominal exercises during pregnancy didn't meaningfully change the gap or pelvic floor symptoms. Talk with your pelvic health physiotherapist and prenatal provider about what fits your pregnancy.

When should I see a pelvic floor physiotherapist for diastasis recti?

See one if you have pain, leaking, a heavy feeling in your pelvis, a bulge that isn't settling, or you're unsure which exercises are right for you. An assessment looks at how your core and pelvic floor are working, not just the size of the gap.