The vague pain in the stomach at 16 weeks of pregnancy may be caused by physiological factors of uterine enlargement, or it may be caused by pre-eclampsia or non-pregnancy diseases, such as gastroenteritis and other gastrointestinal diseases, ureteral diseases such as ureteral stones, and gynecological diseases such as pelvic inflammatory disease and ovarian cysts. I. Physiological factors: 16 weeks of pregnancy belongs to the middle of pregnancy, when the fetus gradually develops and grows, the uterus is also gradually increasing in size with the growth of the fetus. The uterus becomes bigger and easily causes obvious pulling and squeezing on the surrounding tissues and uterine ligaments, which leads to vague pain in the stomach. Usually, the pain caused by this condition is mild and should be relieved as long as the pregnant woman gets enough rest and avoids maintaining a position for a long time, so there is no need to worry too much. Pathological factors: 1. Pre-eclampsia: If the symptoms of vague pain in the stomach continue to not ease and have a tendency to worsen, or accompanied by vaginal bleeding symptoms, it is likely that a pre-eclampsia has occurred. If the abdominal pain cannot be relieved and has increased, or if the vaginal bleeding increases, it generally means that the abortion is inevitable and the pregnancy needs to be terminated; 2, non-pregnancy diseases: the vague pain in the stomach at 16 weeks of pregnancy may also be caused by other non-pregnancy diseases, such as kidney stones, ureteral stones and other urinary tract diseases, gastroenteritis, gallbladder disease, etc. The pain may be caused by other non-pregnancy diseases, such as kidney stones, ureteral stones and other urinary diseases, gastroenteritis, cholecystitis and other digestive diseases, or pelvic inflammatory disease, uterine fibroids, ovarian cysts and other gynecological diseases. For such cases, you need to go to the hospital in time to get a clear diagnosis from the doctor and use medication under the guidance of the doctor to avoid serious consequences and endanger the health of mother and child. After pregnancy, it is important to cooperate with the doctor for regular maternity checkups, so that the physical condition of the pregnant woman and the fetus can be known in time and problems can be corrected as soon as possible to avoid unnecessary effects.