Everyone (excepting possibly Jane Fonda) develops a diastasis recti after pregnancy. That's a big, fancy medical term that describes the drifting apart of the rectus muscles, (your 6-pack ab muscles) after expanding during pregnancy.
The condition is physiological, not pathological. That means that it is normal and expected. It’s sort of the cost of doing business for your body. During pregnancy, the muscles drift to the sides (laterally) to make room for the developing fetus. It's kind of like suspenders on a man who gains weight – say from 150 to 250 pounds – the suspenders drift to the sides. After pregnancy, the muscles do migrate back to the middle, as the skin shrinks and pressure inside the belly decreases. But they never quite reach the midline, as they were pre-pregnancy.
The consequences of the diastasis are both cosmetic and functional. Cosmetically, the belly bulges forward. This is almost always combined with excess skin and fat on the abdominal wall. Functionally, the rectus muscles are the most important stabilizers of the front of the spine. When they drift laterally, the alignment of the chest, abdomen and pelvis is altered. The chest bends back, developing a condition called “lordosis,” the belly bulges forward, and the buttocks drift backwards. In addition, the external oblique muscles insert into the rectus muscles and lose their normal tone. That hurts the efficiency of that muscle.
The combination of this situation is poor posture, low-back pain and decreased abdominal strength.
The indications for operating are usually cosmetic. Functional improvements such as improved posture, less low-back pain, and increased abdominal strength are byproducts of the surgery. I have rarely repaired the diastasis without doing a tummy tuck. That's because usually we use a hip bone to hip bone incision and remove excess skin at the same time. A few times, I used small incisions and fixed the muscle using an endoscope (an instrument with a camera on the end of it). Not a great procedure, however.
There were about 120,000 tummy tucks in the US last year. There are no stats on diastasis repair alone, but my guess is probably less than 100.
The tummy tuck is a high satisfaction procedure. But there are a lot of complications. Hematomas (bleeding) occur in as many as 5%, blood clots in the legs (DVTs) in as high as 2%, seromas (collection of clear, blister fluid) in as high as 15%. That's why I strongly argue that the procedure should be done in hospital with an overnight stay. Drains stay in for 3 days. And it's not a good idea to combine this procedure with other procedures other than liposuction of the flanks.
Tummy tucks are a high-satisfaction procedure, but you’ve got to be well motivated to undergo it.