Hidden pain in the left side of the abdomen in the second month of pregnancy may be related to inflammation of the left adnexa, ectopic pregnancy on the left side, chronic gastritis and so on. 1. Inflammation of the left adnexa: there may be inflammation in the left adnexa or torsion of the corpus luteum cyst, etc. As the embryo grows and develops in the uterine cavity and the uterus enlarges, it may pull on the adnexa, resulting in vague pain in the left abdomen. 2. Left ectopic pregnancy: if the fertilized egg is deposited in the left fallopian tube, with the increasing size of the embryo, the fallopian tube is forced to overexpand, and the left abdominal pain may also occur. 3. Chronic gastritis: if the lesion site is at the bottom of the stomach, when the gastric mucosa is stimulated by inflammation and damage occurs, it will cause the left abdominal pain. When the left abdominal pain occurs, it is recommended to consult a doctor in a timely manner, follow the doctor’s instructions for further examination to find the cause, under the doctor’s comprehensive analysis, choose a reasonable treatment plan.