The first and most common reason is the increase of estrogen in the body after pregnancy, which makes the gastrointestinal tract peristalsis slow down relatively, so the situation of stomach distension will occur, and often pregnant women also have constipation, it is recommended to give appropriate walks during pregnancy, and eat more fresh fruits and vegetables to promote gastrointestinal tract peristalsis, which will slow down the situation of stomach distension; The second, caused by pre-miscarriage, due to the body progesterone deficiency or after intercourse, after exertion, the smooth muscle contraction of the uterus will also appear vague stomach swelling pain, in the clinical attention should be paid to rest, when necessary, you can do ultrasound, blood tests, according to the results should be given appropriate antifetal treatment.