During IVF, coitus is not recommended after the down-regulation injection. There are two main reasons: first, to ensure the health of sperm quality, because it is only the period of down-regulation, and the in vitro culture of fertilized eggs has not yet been carried out. The time of down regulation, specific need to be decided according to each person’s physical condition. In order to ensure that healthy sperm can be retrieved when the fertilized egg culture is carried out at a later stage, sexual intercourse should be avoided during this period of time. Secondly, the impact of the down regulation itself, the purpose of the down regulation is to control the luteinizing hormone in the body through the drug, which can effectively delay the development of the egg, to avoid the emergence of independent ovulation. Can effectively increase the number of follicle recruitment, for the later retrieval of eggs can collect more mature eggs. In the process of sexual life, sexual stimulation will lead to changes in the hormone levels in the female body, which is not conducive to maintaining normal hormone levels, and is prone to inducing autonomous ovulation, leading to the effect of lowering the regulation to be affected.