Mild stomach pain in the first month of pregnancy may be caused by normal physiological phenomena, ectopic pregnancy and pre-miscarriage. 1. Normal physiological phenomenon: some women may experience mild stomach pain in the first month of pregnancy, which may be related to the embryo’s implantation and uterine enlargement, etc. It is usually a normal phenomenon and can be recovered by itself, so there is no need to worry too much. 2. Ectopic pregnancy: If the patient has ectopic pregnancy, it will also lead to mild pain in the stomach in the first month of pregnancy, and the pain may get worse gradually. 3. Pre-eclampsia: In addition, if a woman does not take good care of her pregnancy, strenuous exercise and sexual intercourse may induce pre-eclampsia, resulting in mild pain in the stomach, which may gradually worsen. Therefore, if the patient has mild stomach pain after one month of pregnancy and it cannot be improved for a long time or has worsened, she should go to the hospital in time for treatment.