Diastasis Recti (Mommy Tummy)

Diastasis recti — sometimes called abdominal separation or, informally, ‘mommy tummy’ — refers to a stretching of the linea alba, the band of connective tissue running down the midline of the abdomen between the two rectus abdominis muscles. Some degree of this stretching happens in nearly every pregnancy and is a normal physiological adaptation rather than an injury. What matters most for recovery is not simply how wide the gap is, but how much tension the linea alba can generate across it — a detail that often gets overlooked in generic gap-width advice.

What the linea alba is and how it stretches

The linea alba is made of layered collagen fibres that normally run in a tight, interwoven pattern, giving it the tension needed to transfer force between the left and right sides of the abdominal wall when you move, lift, or breathe. As the uterus grows throughout pregnancy, this tissue is placed under sustained stretch, and the distance between the two rectus muscles widens to accommodate that growth. This is an expected and necessary adaptation — without it, the abdominal wall could not expand to make room for a growing baby.

Why tension matters more than gap width

After birth, the linea alba does not automatically regain its pre-pregnancy tension just because time passes; tension is regained through how the tissue is loaded and trained. This is why gap width alone is a limited measure: a narrow gap with poorly regained tension can still dome or bulge outward under load, while a wider gap with well-restored tension may transfer force effectively and cause no functional problem at all. Doming or coning — a ridge or bulge that appears along the midline during a sit-up, a cough, or picking up a toddler — happens when rising intra-abdominal pressure pushes outward against a section of linea alba that cannot yet resist that pressure. Reducing that doming pattern, rather than chasing a specific gap measurement, is generally a more meaningful marker of progress. This is also why two people with an almost identical gap measurement can have very different experiences — one may lift, sneeze, and exercise without any bulging at all, while the other notices doming with the simplest movements, because the difference lies in how the tissue responds under load rather than in the distance between the muscles.

Why crunches and breath-holding can worsen things early on

Traditional curl-up or crunch exercises pull the rectus abdominis muscles toward each other in a way that bows the connective tissue between them outward, particularly when the linea alba does not yet have the tension to resist that load — repeating this pattern can reinforce doming rather than resolve it. Holding your breath while bracing for a lift (a Valsalva manoeuvre) sharply increases intra-abdominal pressure and directs that pressure outward and downward, against both the linea alba and the pelvic floor, at exactly the moment those structures may be least prepared to manage it. This is why early diastasis rehabilitation typically shifts away from crunch-style movements and breath-holding, toward exhale-coordinated bracing that manages pressure more deliberately while the tissue regains capacity.

What structured diastasis rehabilitation helps with

• Doming, bulging, or a ‘mommy tummy’ appearance: addressed by rebuilding the linea alba’s ability to generate tension under load, rather than by spot-reducing the area.
• Functional core strength: retraining the deep core as a coordinated pressure-management system, which supports lifting, twisting, and general daily activity.
• Pelvic floor coordination: because the deep core and pelvic floor share the same pressure system, diastasis rehabilitation often improves pelvic floor symptoms as a secondary benefit.
• Related low back discomfort: reducing compensatory overload on the lower back that can develop when the deep core is not managing pressure effectively.

What a thorough assessment involves

Assessment includes manually checking the width of the gap at several points along the midline, but more importantly, feeling the depth and tension of the tissue as you perform a controlled partial curl — this tells your physiotherapist far more about function than width alone. Your physiotherapist will also watch for doming during functional movements like getting up from lying down or carrying a load, and will assess your breathing and bracing patterns, since these directly influence how pressure is managed through the midline.

How treatment works

Rehabilitation usually starts with isolated, low-load activation of the deep core and pelvic floor together, coordinated with your breath, before progressing to more functional and eventually higher-load movement as the tissue demonstrates it can manage that pressure without doming. This is a graded process rather than a fixed program — many people notice meaningful change over weeks to a few months of consistent, well-dosed rehabilitation, though timelines vary based on how many pregnancies you’ve had, tissue quality, and consistency of training. Surgical repair of diastasis recti is available but is generally reserved for situations where significant functional impairment or a related hernia persists despite a genuine course of rehabilitation — for most people, structured non-surgical rehab is the appropriate first step.

Who this can help

• Anyone noticing doming, bulging, or a gap along the midline after pregnancy.
• People who feel their core is disconnected or weaker than before pregnancy.
• Anyone told they have diastasis recti and unsure what to actually do about it.
• People preparing to safely return to running, lifting, or other higher-load exercise postpartum.
• Anyone planning a future pregnancy who wants to enter it with a stronger, more responsive core.

Diastasis rehabilitation is a core part of our pelvic health physiotherapy care for the postpartum period. You can book an appointment at our High Park, Toronto clinic to have your core assessed and start a structured plan.