Small stomach pain 18 days after delivery is usually caused by uterine contractions. After giving birth, whether a woman gives birth naturally or by cesarean section, she enters the puerperal period, during which the uterus gradually recovers from the large uterus of pregnancy to the small uterus of the non-pregnant state, which is accomplished solely by uterine contractions. Therefore, during the puerperium, the uterus is constantly contracting and recovering, and women who are more sensitive may experience pain in the lower abdomen, which is also called tummy ache. In primigravida, this pain is usually not sensitive enough, but in menstruating women, this pain is very sensitive, but most women’s will be relieved in a week or so, but it does not mean that after a week there will be absolutely no abdominal pain caused by uterine contraction. So 18 days after giving birth to small stomach pain, if there are no other abnormalities, such as vaginal bleeding or unbearable pain, is caused by uterine contraction, when the vaginal bleeding or unbearable pain, it may not be the uterine cavity with residue, such as uterine metaphysis discharge is not sharp and so on caused. So when the 18 days after the delivery of small stomach pain, do not worry should go to the hospital to check to see if there is no abnormalities, if it is a normal puerperal changes, there is no need to do any special treatment.