The vague pain in the abdomen on the 35th day of pregnancy is considered to be caused by normal phenomenon, pre-miscarriage, gastroenteritis and other reasons. 1. Normal phenomenon: early pregnancy due to the embryo has just landed, may stimulate the uterus, causing vague pain in the abdomen, this is a normal phenomenon. 2. Pre-eclampsia: A vague pain in the abdomen in early pregnancy, accompanied by a feeling of hardness and tightness of the stomach, may be a pre-eclampsia, which should be kept in a timely manner. 3. gastroenteritis: 35 days pregnant women because of poor diet, may cause gastroenteritis, causing vague pain in the abdomen, but also vomiting, diarrhea and other phenomena. To summarize, if you encounter a hidden pain in the abdomen on the 35th day of pregnancy, you should go to the hospital in time to clarify the cause of the disease, do not wait at home, so as not to cause adverse consequences.