Core training in pregnancy: safe ab work, diastasis and the pelvic floor

"Core" can mean a lot of things in fitness, from visible abs to a punishing plank challenge. In pregnancy, it helps to think of it differently: as a team of muscles that wraps around your middle and holds you up. Your deep abdominal muscles, the muscles along your spine, your breathing muscle (the diaphragm) and your pelvic floor all work together. Pregnancy stretches and loads that team in new ways, so the goal shifts from building a six-pack to keeping the whole system strong, supple and coordinated.

Is it safe to work your abs while pregnant?

Resistance training, which includes core work, is encouraged in pregnancy as long as it follows basic safety precautions.^[1] What changes is how you load your abdominal wall. As the bump grows, the wall stretches to make room, so exercises that once felt easy can put a lot of strain on it.

The Canadian guideline recommends that people who notice a visible separation of their abdominal muscles seek advice from a physiotherapist and avoid abdominal strengthening exercises such as curl-ups, which may make it worse.^[1] The IOC expert group also advises avoiding the Valsalva manoeuvre (straining while holding your breath) and excessive pressure on the pelvic floor during strenuous training.^[3]

Eggsports applies these principles in every pregnancy session. We leave out loaded forward bending (such as weighted sit-ups) and exercises that create high pressure inside the abdomen, at every stage of pregnancy, and from week 16 we also leave out exercises lying on your back or front, and twisting under load.

What is diastasis recti, and is it normal in pregnancy?

The IOC expert group defines diastasis recti abdominis as a separation of the two rectus abdominis muscles along the midline, the linea alba.^[2] How common it is depends on how and when it is measured, but it is clearly a normal part of pregnancy for many people:

• In a Norwegian study of 300 first-time pregnant women, 33% had a separation of at least two finger-widths at week 21.^[4]
• In a Portuguese ultrasound study of 84 first-time mothers, every participant met the definition of diastasis at week 35. By six months after birth, the figure had fallen to 39%.^[5]
• Across studies, reported rates in the second and third trimesters range from 27% to 100%.^[2]

Two findings may be reassuring. Neither study found that people with diastasis had more lower back or pelvic pain after birth than those without it.^[4][5] And there is no agreed cut-off yet for what counts as a diastasis, or where to measure it.^[2]

You may notice a ridge or dome running down the middle of your belly when you sit up, lift your head from the floor or strain. That visible bulging is a cue to change how you move: roll onto your side to get up, swap curl-ups for gentler options, and ask a physiotherapist for tailored advice.^[1] After pregnancy, our diastasis self-check guide explains how to check the gap and when to see a professional.

Which core exercises are safe during pregnancy?

The research on specific core exercises in pregnancy is still thin. A systematic review found that exercise during pregnancy reduced the presence of diastasis by 35%, but the included studies were of poor quality, and the authors concluded that exercise may or may not help.^[7] The IOC expert group found no studies that tested whether diastasis can be prevented or treated with exercises during pregnancy.^[2] The Canadian guideline notes that continuing aerobic exercise such as walking is linked with lower odds of developing diastasis.^[1]

So the focus is on movements that train the core to do its everyday job, holding you steady while you breathe and move, without big spikes in pressure. These are some of the exercises we like:

Which ab exercises should you avoid in pregnancy?

These are the movements most worth swapping, and why:

The IOC expert group notes that symptoms from lying on your back become more likely after 28 weeks, and suggests tilting the torso to about 45 degrees or exercising in side-lying, sitting or standing positions.^[3] Eggsports moves core work off the back from week 16, as a cautious middle ground between guidelines.

You'll find more on breathing and position changes in our guide to exercise in the second and third trimester, and on core moves within a strength routine in lifting weights while pregnant.

How does your pelvic floor fit into core training?

The evidence here is unusually strong for pregnancy exercise research. A Cochrane review found that continent pregnant women who did pelvic floor training were probably 62% less likely to report urinary incontinence in late pregnancy, and slightly less likely three to six months after birth.^[8] A meta-analysis including exercise programmes with pelvic floor training found the odds of incontinence roughly halved during pregnancy and reduced by about a third after birth.^[9] The benefit was clearest for preventing leaks in people who were not leaking to begin with.^[9]

Guidelines reflect this. The Canadian guideline recommends daily pelvic floor training and instruction in proper technique.^[1] NICE recommends encouraging everyone who is pregnant to do pelvic floor training, and considering a supervised three-month programme from week 20 for those with a first-degree relative, such as a mother or sister, who has pelvic floor problems.^[10]

Technique matters because it's easy to get wrong. The IOC expert group notes that several studies found more than 30% of women could not contract their pelvic floor correctly at their first consultation.^[2] The IOC's recommendation is sets of 8 to 12 close-to-maximal contractions, three times a day, on most days, and to contract the pelvic floor before and during heavier lifts.^[3]

To find the right muscles, sit or lie comfortably and imagine gently lifting and closing around the vagina and back passage, as if holding in wind. Lift, hold for a few seconds while breathing normally, then let go completely. The release is as important as the squeeze. Our pelvic floor exercise timer guides you through slow holds and quick squeezes.

If you notice leaking, a feeling of heaviness or bulging in the vagina, or pelvic pain, a pelvic health physiotherapist can assess you and tailor a programme. NICE recommends supervised programmes for pregnant people who already have stress or mixed urinary incontinence.^[10]

How should you breathe during core exercises?

Breath is the thread that ties the core together. Holding your breath to brace raises pressure inside the abdomen and on the pelvic floor, which the IOC expert group recommends avoiding in strenuous training during pregnancy.^[3] In Eggsports sessions, every exercise is cued with the same reminder: exhale on effort; never hold your breath.

Breathing practice on its own also counts as core work. A few minutes with our breathing timer is a calm way to reconnect with your diaphragm and pelvic floor, especially on days when a full session feels like too much. You can check which stage of pregnancy you're in with our pregnancy week calculator.

If your core work is bringing on pain at the front or back of your pelvis, read about pelvic girdle pain. And for the full picture of moving through pregnancy, see our complete guide to exercise during pregnancy.