Diastasis recti might cause a bulge in the middle of the abdomen where the two muscles separate. The condition might be noticeable only when the abdominal muscles are tense, such as during coughing. Diastasis recti develops in late pregnancy, but is usually most noticeable right after delivery. The muscle separation often lessens in the months that follow. However, some degree of separation might remain up to a year after childbirth and beyond. Diastasis recti can weaken the abdominal muscles, causing lower back pain and making it difficult to lift objects or do other routine daily activities.