The pain in the stomach when the baby is about to be born is a regular contraction of the uterus, which is a hardening of the stomach and is accompanied by a painful sensation. Some people may also experience lower back pain and the urge to have a bowel movement during this period. At the beginning, the pains occur once every 30-60 minutes, and each pain lasts for a few seconds or a dozen seconds. As the labor progresses, the duration of pain will gradually increase and the interval will gradually become shorter, about 10 minutes, and the pain will last for about 30 seconds each time. When the opening of the uterus is almost complete, the pain will be once in 1-2 minutes and last for about 50 seconds each time, and continue in this way until the birth.