You posted this in Pregnancy so I'm assuming that means that you are pregnant. Congratulations. How far along are you? The abdominal muscles will undergo stretching over the course of a pregnancy. From the information you've provided, you are obviously much more physically fit than I ever was, which could explain why you're noticing the muscle changes moreso than I ever did. I've always been a lot on the flabby side, so while the visual of a growing belly was obvious, my muscles didn't complain because they were already relaxing on the job, lol.
at 5:48 AM on May. 16, 2011