Why Closing the Gap is the Wrong Goal for Tummy Separation Recovery

What the latest research is telling us, and why it should change the way we think about “bouncing back” after having a baby.

What is a normal gap?

A 2023 study measured the gap between the two sides of the abdominal muscles in women who had never been pregnant. At the belly button, the average was just under 9mm. In perfectly healthy women, it ranged from 6.6mm all the way to 11mm.

This is the baseline we've been comparing postpartum bodies to.

A separate study measured first-time mums at 6 months postpartum and found the average gap at the belly button was 22mm, with up to 28mm still considered within the normal range for that stage. That's the midpoint. Half of the women had more, half had less. The researchers noted this was simply what normal looks like at that point in life.

That gap is more than double the pre-pregnancy average. And yet women are being told they haven't recovered because their gap hasn't returned to pre-pregnancy measurements.

Comparing a six-month-postpartum body to the body of a woman who has never been pregnant isn't a fair comparison. They're not the same body. They're not supposed to be.

We don't expect a woman's body to reverse every change it goes through. We don't expect breasts to disappear after menopause. We understand the body moves through life stages. The same logic applies here. After having a baby, there is a new normal, and that new normal is supported by the research.

The gap isn't really the point

Multiple studies over the past few years have landed on the same finding: the size of the gap at rest doesn't reliably tell us whether a woman is in pain or struggling to function.

A 2022 study looked at women in the first few days after birth and found that pelvic pain was not linked to the size of the gap at rest. It was also not linked to whether the belly domed or coned when they tried to activate their core.

What was linked to pain? The inability to draw the gap in when the muscles fired. When women in pain tried to engage their core, the gap stayed wide. Women without pain could brace their muscles and pull the gap in significantly.

Same size gap. Completely different ability to use those muscles.

That pattern showed up again in a 2023 study at 12 months postpartum. Women with ongoing back pain and reduced function had two things in common: a wider persistent gap and significantly weaker abdominal muscles. They could do only about half as many sit-ups in 30 seconds as the women who had recovered well.

Did the weak muscles allow the gap to stay wide, or did the wide gap cause the muscles to weaken? The evidence points toward the first one, and that has significant implications for how we approach recovery.

The sit-up ban: where it came from and why it may be causing harm

The restriction on sit-ups after tummy separation became so widespread that most women accept it without question. It traces back to one foundational study, and that study excluded any woman who regularly performed sit-ups from the participant pool.

The research that told us sit-ups were dangerous never actually looked at women who did them.

The abdominal muscles that sit-ups train play a critical role in the early postpartum period, specifically because the connective tissue running down the middle of the abdomen hasn't yet regained its strength. Without that structural support, the abdominal muscles need to do the bracing job themselves.

If a woman is told to avoid the exercises that build those muscles, they become weaker. The gap becomes harder to control. The core becomes less stable. Pain and dysfunction become more likely, not less.

The potential cascade looks like this: tummy separation develops in pregnancy, the woman is told to avoid sit-ups, abdominal muscles gradually weaken, muscles can't brace the abdomen or stabilise movement, more pain and a higher gap, the woman gives birth with even weaker muscles, the early recovery window closes without the right support in place.

None of this means sit-ups are appropriate for every woman from day one. Timing, load progression, and individual circumstances always matter. But blanket avoidance? The evidence doesn't support it and may be making things worse.

Your hormones are doing the heavy lifting

One of the most reassuring things in this research is what happens at the tissue level in the weeks after birth.

During pregnancy, your body produces a stretchy type of connective tissue so your abdomen can expand. At the end of pregnancy, the gap between your abdominal muscles is often 6-7cm wide because it had to be.

When you give birth, your hormones shift dramatically. Your body starts switching over to a structural, load-bearing type of connective tissue. Day by day, it's quietly rebuilding.

Your body has that repair program running already. It doesn't need to be triggered by exercise. It's hormonally driven.

In the very early weeks, that connective tissue is still new and fragile. What's appropriate to load at six weeks is very different from two weeks, and the body needs time to do its job before we start demanding more from it.

Abdominal binding can be genuinely useful in that early window. Not as a permanent solution, but as temporary support while the tissue is rebuilding. As the structural tissue returns, the body takes back its own load-bearing role.

What actually matters for recovery

The gap size at rest is not a reliable indicator of how well a woman is recovering.

Visual doming or coning when the core activates is not linked to pain or poor outcomes.

What does matter is whether the muscles can fire, brace, and take load, and building that strength takes progressive exercise, not avoidance of it.

Timing matters enormously. The early weeks after birth are hormonally and structurally different from three or six months postpartum. A one-size-fits-all protocol doesn't serve women well.

Function, strength, pain levels, and the ability to move freely through daily life are far more meaningful measures of recovery than any gap measurement.

If you're navigating this, a women's health physio who stays current with the evidence is the right person to guide you. Not because your body is broken, but because you deserve care that actually reflects how your body works.

Wang Y, Wang H. Systematic review and meta-analysis of the inter-recti distance on ultrasound measurement in nulliparas. J Plast Surg Hand Surg. 2023.

Mota P, Carita AI, Bo K. Normal width of the inter-recti distance in pregnant and postpartum primiparous women. Musculoskeletal Sci and Pract. 2018.

Starzec-Proserpio M et al. Association Among Pelvic Girdle Pain, Diastasis Recti Abdominis, Pubic Symphysis Width, and Pain Catastrophizing. Phys Ther. 2022.

Tuominen R et al. Low back pain and motor control dysfunction after pregnancy: The possible role of rectus diastasis. Int J Abdominal Wall and Hernia Surgery. 2023.

Keshwani N, Mathur S, McLean L. The impact of exercise therapy and abdominal binding in the management of diastasis recti abdominis in the early post-partum period. Physiotherapy Theory and Practice. 2019.

Boissonault & Blaschak, 1988. Incidence of diastasis recti abdominis during the childbearing year. Physical Therapy.

Depledge J, McNair P, Ellis R. Exercises, Tubigrip and taping: can they reduce rectus abdominis diastasis measured three weeks post-partum? Musculoskeletal Sci Pract. 2021.