The big belly in the first month of pregnancy is considered to be caused by over-nutrition, and the possibility of hyperemesis gravidarum and uterine fibroids cannot be ruled out. Excessive nutrition, normal women in the first month of pregnancy stomach is usually not obvious, but if during pregnancy to consume too much high-calorie diet, exercise is reduced, may lead to the accumulation of abdominal fat, thus appearing in the first month of pregnancy belly big situation. Chylothorax is a benign gestational trophoblastic disease, which is mainly formed by the development of an abnormal fertilized egg. The causative factors are related to nutritional status, previous history of chylothorax, age, etc. Patients will experience symptoms such as postmenopausal vaginal bleeding and abnormal uterine enlargement, which will result in the uterus being larger than the month of menopause due to the rapid enlargement of the uterine cavity and the accumulation of blood in the uterine cavity, leading to the development of a big belly in the first month of pregnancy. In addition, if you are suffering from uterine fibroids and other diseases, when the uterine fibroids are too large, you will also appear to have a larger stomach in the early pregnancy. For women with a large stomach in the first month of pregnancy, it is recommended that they seek medical attention for a definitive diagnosis, in addition to ruling out over-nutrition.