The abdominal muscles form a strong but elastic “wall” behind which a baby can grow safely in the uterus. The abdominals also help to support the spine and assist in good posture. In about 30% of pregnant women, the central muscles of the abdomen (the rectus muscle) will separate during pregnancy due to the increasing tension of the growing baby. This is called separation of the rectus muscles of diastasis. It is very important to determine whether there is separation, because certain abdominal muscle exercises can make the separation worse. Any separation, depending on its width and length, needs to be evaluated to address exercises in the appropriate supporting abdominal muscle.