It is not uncommon for pregnant women to feel their baby's movements, including the sensation of their baby's breathing. This can be attributed to a few factors. First, as your baby grows, they start developing their respiratory system, which includes practicing their breathing movements. Second, your expanding uterus puts pressure on your diaphragm, causing it to move up and down more noticeably. This can create the sensation that your stomach is moving in and out as if your baby is breathing. While this can be a normal occurrence during pregnancy, it is always best to consult with your healthcare provider if you have any concerns or experience any unusual symptoms. They can provide personalized advice based on your specific situation.