Lack of progesterone for four months without menstruation can be supplemented by oral or intramuscular progesterone, and when progesterone reaches a certain level, menstruation will occur. The main function of progesterone is to induce the endometrium to change from the proliferative phase to the secretory phase, so if the progesterone is too low it will result in the endometrium not being able to shed or shedding incompletely, leading to the lack of menstruation. Progesterone deficiency can be treated with medication, including direct progesterone supplementation or the use of chorionic gonadotropin to promote follicular growth, increase luteal endocrine function, and increase progesterone secretion. If a woman has a lack of progesterone and does not have menstruation for four months, it is recommended that she go to the hospital for a checkup to clarify the cause of the lack of progesterone, and then under the guidance of the doctor, carry out the treatment. Do not take medication without authorization to avoid adverse consequences.