Diastasis recti,  or rectus abdominis diastasis, is defined as a gap of about 2.7 cm or greater between the two sides of the rectus abdominis muscle. The distance between the right and left rectus abdominis muscles is created by the stretching of the linea alba, a connective collagen sheath created by the aponeurosis insertions of the transverse abdominis, internal oblique, and external oblique. This condition has no associated morbidity or mortality.Diastasis of the rectus abdominis muscle most frequently occurs in newborns and pregnant women; however, it may occur in any adult woman or man. In the newborn, the rectus abdominis is not fully developed and may not be sealed together at midline. Diastasis recti is more common in premature newborns. In pregnant or postpartum women, the condition is caused by the stretching of the rectus abdominis by the growing uterus. It is more common in multiparous women (women who have had multiple pregnancies) owing to repeated episodes of stretching. When the defect occurs during pregnancy, the uterus can sometimes be seen bulging through the abdominal wall beneath the skin. Non-pregnant women are more susceptible to develop diastasis recti when over the age of 35 or with high birth weight of child, multiple birth pregnancy, or multiple pregnancies. Additional causes can be attributed to excessive abdominal exercises after the first trimester of pregnancy.Strength training of all the core muscles, including the abdominis recti muscle, may or may not reduce the size of the gap in pregnant or postpartum women.
The authors looked at 8 studies totaling 336 women and concluded: "Due to the low number and quality of included articles, there is insufficient evidence to recommend that exercise may help to prevent or reduce DRAM," or diastasis of the rectus abdominis muscles, also stating that "non-specific exercise may or may not help to prevent or reduce DRAM during the ante- and postnatal periods. "However, a study conducted by the Columbia University Program in Physical Therapy stated: "Ninety percent of non‐exercising pregnant women exhibited DRA while only 12.5% of exercising women had the condition. The mean DRA located 4.5 cm above the umbilicus was 9.6 mm (± 6.6) for the exercise group and 38.9 mm (± 17.8) for the non‐exercise group. The mean DRA located at the umbilicus was 11.4 mm (± 3.82) for the exercise group and 59.5 mm (± 23.6) for the non‐exercise group. The mean DRA located 4.5 cm below the umbilicus was 8.2 mm (± 7.4) for the exercise group and 60.4 (± 29.0) for the non‐exercise group. "Nevertheless, the following exercises are often recommended to help build abdominal strength, which may or may not help reduce the size of diastasis recti:
Core contraction – In a seated position, place both hands on abdominal muscles. Take small controlled breaths. Slowly contract the abdominal muscles, pulling them straight back towards the spine. Hold the contraction for 30 seconds, while maintaining the controlled breathing. Complete 10 repetitions.