Causes of non-menstrual uterine bleeding

Abnormal uterine bleeding outside the menstrual period is usually caused by ovulation-related bleeding, primarily due to insufficient estrogen. Bleeding before or after menstruation may result from luteal phase deficiency, inadequate pregnancy hormones, or cervical lesions. In the female menstrual cycle, estrogen has two peaks: the first occurs before ovulation and the second before menstruation.