Women who want to check their luteal function usually need to do so about 1-2 weeks before their menstrual cycle, when they are in the luteal phase of their menstrual cycle and the test results are relatively the most accurate. Luteal function plays a very important role in female endocrine secretion, and if there is insufficient luteal function, it will affect the normal pregnancy and menstruation of women. It is better to check the luteal function about 1 week after ovulation. There are many reasons for luteal insufficiency, such as insufficient secretion of hormones during the follicular phase, ectopic endometrium or frequent or multiple miscarriages. Insufficient luteal function can also be caused by endocrine diseases, such as hypothyroidism and hyperprolactinemia.