1, chromosomal abnormalities, both husband and wife may Miscarriage is caused in large part by fetal chromosomal abnormalities, chromosomes are the carrier of genetic genes, any number of abnormalities and structural changes can cause an imbalance of genetic material, if one or both spouses have chromosomal abnormalities, it is possible to cause fetal chromosomal abnormalities through genetics and thus cause miscarriage and sterilization. Therefore, chromosome examination of both spouses before pregnancy is very necessary. 2, sperm and egg aging, embryonic dysplasia sperm for too long “sperm”, eggs as women age will make both aging, resulting in embryonic dysplasia. The most important thing is to have the right age and the right time to conceive, which is the key to a good birth. 3, maternal immune abnormalities immune factors are important factors in habitual miscarriage, including the common maternal lack of closed antibody, maternal presence of anti-cardiolipin antibody and mother-child blood type, to actively find the cause and timely and effective treatment to deal with. 4, environmental factors ionizing radiation, high temperature environment, noise pollution, frequent exposure to reproductive toxic substances, etc. can indirectly or directly affect the normal development of the embryo fetus, miscarriage, suspension, premature birth, fetal malformation, etc. 5, maternal microbial infections Protozoa, bacteria, Chlamydia trachomatis, mycoplasma, syphilis spirochetes, gonococci and other pathogenic microorganisms can cause endometrial infection and intrauterine infection, causing spontaneous abortion. 6, maternal reproductive organ malformation, fetal growth restriction uterine malformation, uterine fibroids, uterine diaphragm, loose endocervical opening and uterine cavity adhesions, etc., can affect the normal development of the fetus and lead to bedtime obstruction and early spontaneous abortion. 7, female endocrine disorders after fertilization of the sperm and egg, the fertilized egg must be supported by endocrine hormones to grow and develop normally. Insufficient secretion of progesterone can lead to inadequate preparation of the endometrial secretion and prevent implantation of the pregnant egg. 8. abnormal sperm, abnormal fertilization, and poorly developed fertilized egg There are problems with sperm quality, such as high sperm malformation rate, low sperm vitality, and heavy sperm agglutination, etc. The degree of severity will lead to infertility, but if it is just at the critical point, it can barely conceive, but the quality of the fertilized egg will be greatly reduced, and through selective elimination, spontaneous abortion will also occur. In addition, the presence of asymptomatic infections in the male reproductive tract can impair the ability to conceive, interfere with sperm-egg union or cause spontaneous abortion of the developing embryo. Therefore, routine male semen examination before conception is very necessary, and it is also necessary to actively exclude unfavorable environmental factors such as heat, radiation, reproductive toxicity, and to correct bad behavioral habits.