Pregnancy does not permanently alter body fat proportions. The tummy is stretched out, of course, and the body swells during pregnancy, but there is no net gain or loss of fat cells. This fact explains why, after losing their weight after pregnancy, women find that their body shape is unchanged. The abdominal skin and muscles have been stretched, so the skin tone will not be as tight as it was, and there is likely to be some degree of abdominal "pooch" due to stretching of the muscles, but even in the tummy, there is no fat that was not there before.