The factors affecting the fertilization of the egg are: 1, the factors of the fertilized egg itself, the sperm in the fertilized egg has chromosomal abnormalities, forming a fertilized egg but not successfully bedded, with menstruation out of the body, called biochemical pregnancy. 2, the body’s sex hormone secretion is not enough, luteal insufficiency caused by progesterone secretion, so that the embryo can not be normal bedding and growth. 3, tubal incompetence, the fertilized egg can not pass through the fallopian tube into the uterus for bedding, easy to cause ectopic pregnancy. The first of these is the fact that the woman’s body is negative for closed antibodies, and the immune system will swallow or attack the embryo, thus affecting the embryo’s implantation.