The vague pain in the stomach in the third month of pregnancy may not be abnormal, or it may be a pain caused by pre-eclampsia or other diseases combined with pregnancy, which needs to be judged according to the symptoms.1. Normal: As the pregnancy week increases, the uterus gradually increases in size and the ligaments produce pulling, which may lead to vague pain in the stomach. Most of them appear in the middle and later stages of pregnancy, only a few women may appear in the third trimester, and this feeling usually lasts for a short time. If there is no vaginal bleeding and other abnormalities, you can observe and take regular pregnancy tests, pay attention to rest and avoid strenuous exercise; 2. Pre-eclampsia: If pre-eclampsia occurs in the third month of pregnancy, there will be vague stomach pain and vaginal bleeding at the same time. It is recommended to seek medical advice, perform blood HCG and ultrasound examination, take oral medication for fetal preservation treatment, pay attention to bed rest, strengthen nutrition, if abdominal pain is aggravated or accompanied by bleeding, miscarriage may be inevitable and need to terminate the pregnancy in time; 3, combined diseases of pregnancy: combined pelvic inflammatory disease or digestive system diseases during pregnancy, such as acute gastroenteritis, appendicitis, etc., will also appear vague pain in the stomach, it is recommended to combine It is recommended to seek medical advice in time to clarify the specific causes and take targeted treatment. In the third month of pregnancy, the fetus is still unstable, so you should pay attention to rest, avoid strenuous activities and strengthen nutrition in daily life. If abdominal pain persists or worsens, you should seek medical attention to identify the cause so as not to delay treatment.