Bleeding in the down regulation period is considered to be related to progesterone withdrawal bleeding, down regulation failure, etc. Generally speaking, when the amount of bleeding is less than the usual amount of menstruation, it means that the possibility of success is relatively large, but due to individual differences in the specific situation, we need to improve the ultrasound and other related tests to assess the success of the down regulation or not. 1. Progesterone withdrawal bleeding: down-regulation is the down-regulation of the pituitary gland through drugs to avoid spontaneous ovulation, can increase the quality of follicles, down-regulation will increase the level of exogenous gonadotropins, when the effect of the drug subsides, the hormone level gradually decline will appear progesterone withdrawal bleeding, generally less bleeding. 2. Failure to regulate: If the patient has menstrual vaginal bleeding, it is considered to be the failure of women to regulate, and at the same time, improve the ultrasound examination, there are generally no multiple follicles of similar size, and the endometrium has not reached the corresponding thickness. For women who bleed during the period of adjustment, it is recommended that they go to the reproduction department of regular hospitals for consultation, and after clarifying the cause of the disease, they should be actively treated under the guidance of doctors in order to improve the success rate of IVF.