There are two main possibilities to consider when a feeling of cramping in the lower abdomen occurs around the third trimester of pregnancy: the first possibility is that the patient is experiencing a preterm miscarriage. The cramping sensation in the lower abdomen is caused by the patient experiencing contractions, in which case the patient may have vaginal bleeding. The patient must have a gynecological ultrasound to see if the embryo is still alive in the uterine cavity, and to observe the length of the cervix to see if there is any shortening of the cervix. The second possibility is to consider that the patient may have urinary tract infection or intestinal disease. In this case, the patient mostly has abnormalities such as frequent urination, urgent urination, painful urination or diarrhea, constipation, etc. Selective examination is needed according to the clinical manifestations of the patient. If urinary tract infection is present, routine urinalysis and urological ultrasound should be performed. If there are abnormalities in the stool, a routine stool examination or colonoscopy will be performed depending on the situation.