Certain couples have not been able to get pregnant naturally after marriage, they can choose to do IVF, but IVF fertilization generally has a lower success rate, there are several factors that contribute to this situation: 1. Couples who cannot get pregnant naturally are generally associated with poor quality of eggs or sperms of both husband and wife, for example, if a woman has poor endocrine function of the ovaries, which leads to the failure of the eggs to develop and mature, and to do IVF, it is generally necessary to cooperate with the Doctors use ovulation drugs to help the follicles develop and mature and expel eggs. After some women use ovulation drugs, the eggs may not be fully developed and mature, and the quality of fertilized eggs will be easily affected after egg retrieval; similarly, if it is due to the poor quality of the male partner’s sperm, the quality of fertilized eggs will also be easily affected, and the success rate will be relatively low. 2. In vitro fertilization is generally required for IVF because there are certain differences between the in vitro and in vivo environments, which will also affect the success rate of fertilization. 3. The uterus, after the transfer, will be affected by female endocrine hormones. It will be affected by the female endocrine hormones, which will also affect the success rate of implantation.