Muscle separation, medically called diastasis recti, is a condition where the two long muscles running down the front of your abdomen pull apart along the midline. The gap forms in the strip of connective tissue (the linea alba) that holds these muscles together, and it can range from a narrow slit to a space wider than two fingers. It’s most common during and after pregnancy, but it also affects men and can even be present in newborns.
What Happens Inside the Abdomen
Your “six-pack” muscles, the rectus abdominis, sit side by side and are joined at the center by a band of fibrous tissue called the linea alba. When that band stretches and thins, the two muscle columns drift apart. The muscles themselves aren’t torn. They’re intact but no longer close enough together to work as a unified wall.
During pregnancy, two forces drive this apart. Hormonal shifts cause the connective tissue throughout the abdominal wall to soften and become more elastic, making the linea alba easier to stretch. At the same time, the growing uterus pushes outward with sustained pressure, gradually thinning and elongating the rectus muscles. Ultrasound studies show that by 37 weeks of pregnancy, the gap between the muscles is significantly wider than at 12 weeks, and the muscles themselves are measurably thinner and weaker. In some cases, an anteriorly positioned baby concentrates force on the midline rather than spreading it across the whole wall, accelerating the separation.
Who Gets It and How Common Is It
Muscle separation is remarkably common in pregnancy and postpartum. In a study of first-time mothers, 33% had a measurable separation by 21 weeks of pregnancy and 60% had it at six weeks postpartum. By six months after delivery the rate dropped to 45%, and by 12 months it was still present in about one in three women.
Men develop it too, though less often. Chronic or excessive straining is the usual cause: heavy weightlifting with poor form, persistent constipation, rapid weight gain or loss, or anything that repeatedly spikes pressure inside the abdomen. Obesity is a contributing factor because it places constant outward force on the abdominal wall.
How to Check for It at Home
A simple self-check can give you a rough idea of whether you have a separation and how wide it is. Lie on your back with both knees bent and feet flat on the floor. Place your index and middle fingers side by side on your abdomen, just above your belly button, pointing toward your feet. Slowly lift your head and shoulders off the ground, as if starting a crunch, and feel for a gap or soft dip under your fingers. If you can sink two or more fingers into a groove between the muscles, you likely have some degree of separation. Repeat the check just below the belly button as well, since the gap can vary along its length.
For a clinical diagnosis, ultrasound is the gold standard. Diagnostic thresholds are a gap wider than about 2 centimeters at the belly button or wider than 1.4 centimeters a few centimeters above it. Postpartum ultrasound assessments have found that roughly 85% of affected women show widening of the linea alba, with about 15% showing an actual discontinuity in the midline tissue.
Symptoms and Functional Effects
The most visible sign is a bulge or ridge that runs down the center of your belly, especially noticeable when you contract your abs (like sitting up in bed). Some people describe it as a “doming” or “coning” shape. Beyond appearance, muscle separation weakens the core’s ability to stabilize your trunk, which can affect posture, make everyday lifting harder, and contribute to a feeling of abdominal looseness.
The link between muscle separation and low back pain is debated. A systematic review covering nearly 3,000 patients found that about 39% of included studies reported a positive association between the two conditions, while 61% found no connection. So while some people with diastasis recti do experience back pain, it’s not a guaranteed consequence. Pelvic floor problems, including urinary incontinence, are another commonly reported concern, likely because the deep core muscles and pelvic floor work as a coordinated system. When one part is compromised, the others compensate.
An umbilical hernia frequently accompanies muscle separation because the progressive laxity of the midline tissue creates a weak point near the belly button where tissue can push through.
Recovery Without Surgery
A small separation often resolves on its own within four to eight weeks after delivery. Larger gaps can take six to 12 months of targeted rehabilitation with a specialist physiotherapist. The goal of rehab isn’t necessarily to close the gap completely but to restore tension and control in the connective tissue so the core functions well again.
Programs that focus on deep core stability tend to outperform traditional ab exercises. Effective approaches include abdominal bracing (gently tightening the deep muscles without movement), diaphragmatic breathing, pelvic floor contractions, modified side planks, and glute bridges. These exercises rebuild the deeper layers of the core that act as a natural corset around the midsection.
There’s been longstanding concern about whether exercises like crunches or curl-ups worsen the gap. Recent evidence is more nuanced than the blanket “avoid all crunches” advice you may have heard. One study found that daily curl-ups over 12 weeks didn’t worsen the separation and actually increased abdominal muscle strength and thickness. Researchers have suggested that women with mild to moderate separation shouldn’t be discouraged from head lifts, curl-ups, or twisted curl-ups. That said, exercises should feel controlled, not produce visible doming along the midline. Starting with deep core work and progressing gradually remains the safest path.
When Surgery Becomes an Option
Surgery is considered when the separation causes persistent discomfort that worsens with movement, when the appearance of the abdominal wall is noticeably distorted, or when an umbilical hernia develops alongside the diastasis. Fixing a hernia without addressing the surrounding separation often leads to recurrence because the weakened tissue can’t hold the repair.
For mild to moderate cases, the procedure involves stitching the linea alba and the front of the muscle sheath back together, a technique called plication. For more extensive separation with significant tissue laxity, a supportive mesh may be placed to reinforce the repair. These procedures are sometimes combined with an abdominoplasty when excess skin is also present. Recovery expectations and technique vary based on the severity, so the decision is made on a case-by-case basis after conservative options have been given adequate time.