The stomach pain after taking ovulation injection may be caused by the enlargement of ovaries, ovulation stimulation or increase of estrogen, etc., which needs to be analyzed specifically. 1. Enlargement of ovaries: stomach pain after injections may be caused by the growth and development of multiple follicles in the ovaries at the same time, resulting in the enlargement of the ovaries and pressure on other tissues. 2. Ovulation stimulation: Ovulation itself may also cause stomach pain, which is caused by the rupture of the follicle stimulating the peritoneum and other organs and tissues when the woman is ovulating, and this kind of abdominal pain is usually relatively mild. 3. Estrogen increase: after the use of drugs, due to the growth and development of a number of follicles in the female ovary, this process will cause a large increase in estrogen, which may lead to the occurrence of ascites and other symptoms, stimulation of the peritoneum and other causes of pain. There may be other reasons for the stomach pain after injecting ovulation, it is recommended that once the patient finds himself in a similar situation, consult a doctor in time, complete the relevant examinations and then carry out targeted treatment and therapy.