After the egg-breaking injection, the stomach pain on the 4th day after ovulation may be caused by physiological reasons, pelvic inflammatory disease, gastrointestinal cramps and so on. 1. Physiological reasons: after ovulation, due to the follicular fluid will overflow in the pelvis, at this time may lead to some women to appear the symptoms of abdominal distension. 2. Pelvic inflammatory disease: if women do not pay attention to maintaining perineal hygiene, secondary pelvic inflammatory disease, due to the stimulation of inflammation will lead to the symptoms of abdominal pain. 3. Gastrointestinal cramps: After ovulation, if a woman eats unfresh food or gets cold in the abdomen, it may lead to gastrointestinal discomfort, gastrointestinal cramps and abdominal pain. Women should pay attention to regular gynecological examinations and seek medical attention as soon as possible if discomfort occurs.