There are many reasons for vague stomach pains in 12 weeks of pregnancy, mainly related to physiological contractions and fetal development. However, the possibility of diseases such as pre-eclampsia miscarriage is not completely ruled out. It is best to consult a doctor in time to clarify the cause before treatment. Physiological factors: 1, physiological contractions: in the 11-13 weeks of pregnancy, the uterus has a physiological contraction, more sensitive pregnant women will feel a vague pain in the stomach or appear belly hard and tight performance, generally belong to the physiological, after rest, change position, the symptoms can be relieved; 2, fetal development: in the 12 weeks of pregnancy, the uterus continues to increase, amniotic fluid, increased pressure on the pelvic muscles. Will make some relatively sensitive pregnant women feel vague abdominal pain, which is a normal phenomenon, pain generally does not last a long time, after rest symptoms can be relieved. Pathological factors: 1. Pre-eclampsia miscarriage: if pregnant women do not pay attention to rest during pregnancy, labor intensity or luteal insufficiency, etc., it may trigger contractions, and they will feel a burst of pain in the stomach, and accompanied by vaginal bleeding, then consider pre-eclampsia miscarriage, and should immediately seek medical attention in the company of family members or friends, and can use dydrogesterone for fetal preservation treatment, while paying attention to rest and reducing the amount of activity, and some pregnant women can be successfully preserved; 2. Others: If pregnancy is combined with intestinal diseases and urinary system diseases, abdominal distension and pain or hidden pain may occur, usually accompanied by diarrhea, urinary urgency and painful urination, etc. It is recommended that pregnant women seek medical treatment in a timely manner for causal treatment and avoid using drugs at home on their own. During pregnancy, pregnant women should pay attention to their diet, eat more easily digestible food, avoid eating cold food to cause gastrointestinal discomfort, exercise properly, and do not sit or lie down for a long time. Regular maternity checkups, if there is any discomfort such as increased abdominal pain, you need to go to the hospital for examination in time.