Didrogestrel does not promote ovulation and has no ovulation-promoting effect, but when the ovaries ovulate, there is a significant increase in the secretion of progesterone at this time. At this time, the endometrium will have an obvious role in secretion on top of proliferation, which is conducive to the fertilization of eggs. Therefore, the effect of dydrogesterone at this time is not to promote ovulation, but also to support the function of the corpus luteum after ovulation, which is conducive to the smooth continuation of pregnancy.