The vague pain in the stomach in the fourth month of pregnancy is considered to be a physiological pain. The fetus grows faster in the fourth month of pregnancy, which can lead to pain involving the uterine ligaments or tendons and nerves during this period, but the pain is not particularly serious. During this period, you should try to pay attention to bed rest and do not exercise strenuously, overexertion is likely to aggravate the pain, when the pain is obvious, you can gently touch the belly, which can play a role in promoting blood circulation and reducing pain. If the pain is obvious, you need to do an ultrasound to see if it is caused by an inflammatory infection. Left-sided fallopian tube infection or ovarian cysts can also cause pain in the left side of the stomach, which requires symptomatic treatment to control the development of the disease.