The birth of a child between a man and a woman after marriage is supposed to be a happy event. However, when one of the partners has a certain genetic disease, both parties need to think it over before getting married. It is recommended that genetic counseling be done first to understand in detail the extent of the danger of the genetic disease and the risk of developing it in the offspring. Because some genetic diseases may affect the fetus and lead to serious birth defects, so be careful. 1, unsuitable for childbirth genetic diseases (1) one of the two sexes is a serious autosomal dominant genetic disease, the risk of offspring after marriage is 1/2. These genetic diseases include: hereditary spastic ataxia, tuberous sclerosis, chondrodysplasia, osteogenesis imperfecta, compulsory myotonic dystrophy, facioscapulohumeral progressive myotonic dystrophy, equine Fang syndrome, bilateral retinoblastoma, no iris, retinitis pigmentosa (dominant genetic type), bilateral congenital microphthalmia (dominant genetic type), etc. (2) Both men and women are carriers of the same severe autosomal recessive disorder, in which case the risk of offspring development is 1/4. These genetic disorders include: phenylketonuria, glycogen storage disease, hepatomegaly, congenital total color blindness, microcephaly, etc. (3) Patients in families with high prevalence of specific polygenic genetic disorders. These genetic disorders include patients in families with high prevalence of polygenic genetic disorders such as schizophrenia, manic-depressive psychosis and congenital heart disease, whose offspring are at high risk of developing these disorders. The term “high-incidence family” refers to a family in which one or more parents or siblings, in addition to the patient, have the same disease. 2. If the first child is a child with the following genetic disorders, genetic counseling and fertility guidance are required before preparing to have a second child. (1) Autosomal dominant genetic disorder. One of the parents is a patient and has given birth to one affected child. If the child is born naturally, each child has a 1/2 chance of having the disease, so it is recommended to consider carefully whether to have a second child. If the parents are disease-free and the first child is caused by a new genetic mutation, care should be taken to modify lifestyle habits and reduce or avoid exposure to harmful environmental factors, which may increase the chances of having a normal fetus. Such genetic diseases include chondrodysplasia, osteogenesis imperfecta, osteosclerosis, compulsory muscular dystrophy, Marfon syndrome, bilateral retinoblastoma, aniridia, peroneal muscular atrophy, hereditary spherocytosis, tuberous sclerosis, and primary epilepsy. (2) Autosomal recessive disorders. The risk of having another child is 1/4 for affected parents, 1/2 for carriers, and 1/4 for completely normal if both parents are carriers of the disease-causing gene. third generation IVF is recommended before having another child, and prenatal diagnosis is mandatory. These genetic disorders include: retinitis pigmentosa, congenital glaucoma, congenital total color blindness, congenital deafness, congenital muscle retardation, infantile progressive myelin, polycystic kidney (childhood type), progeria, albinism, phenylketonuria, galactosemia, glycogen storage disease, mucopolysaccharidosis (type H), dementia nigricans, hepatomegaly, pituitary dwarf, hepatocerebro-renal syndrome, microcephaly, etc. (3) X-linked recessive disorders. If the father is a patient, all daughters will get the disease-causing gene and become carriers, while the sons are normal. These diseases include fragile X syndrome, pseudohypertrophic myotonic dystrophy, Becher-type myotonic dystrophy, hemophilia A and B, anhidrotic ectodermal dysplasia, conduit obstructive hydrocephalus, nephrogenic diabetes mellitus, oculocerebrorenal syndrome, orofacial finger syndrome, chronic sarcoidosis, etc. (4) X-linked dominant genetic disorders. Anti-vitamin D rickets and some hereditary nephritis, etc. (5) Chromosomal disorders. The first child is a child with chromosomal disorders, prenatal diagnosis must be done before re-birth. (6) Polygenic genetic disorders and unexplained mental retardation. The more serious polygenic diseases include congenital heart disease, congenital hip dislocation, congenital megacolon, spina bifida, juvenile diabetes, asthma, primary epilepsy, schizophrenia, etc. 3, temporarily unsuitable for childbirth various sexually transmitted diseases, as well as certain infectious diseases hepatitis, tuberculosis, etc., these diseases may affect the quality of offspring, need timely treatment, it is desirable to cure before considering childbirth. Men need to pay attention to the impact of genetic diseases on fertility, but also pay attention to age, many diseases, the environment, poor diet and lifestyle, etc., may also damage the genetic material of sperm, or induce changes in sperm DNA. Nowadays, with the development of molecular genetics, some genetic diseases that are considered unsuitable for fertility, if the causative mutation gene can be found, a normal embryo without genetic mutation can be screened for transfer through third generation IVF technology before embryo implantation genetic diagnosis, and a healthy baby is expected to be born. Therefore, for some families who have already had children with genetic diseases, especially families with children with undiagnosed genetic diseases, if they want to have another child, it is better to keep or provide biological specimens such as blood of the affected child, as well as imaging data of the affected child, etc., in order to help diagnose the disease and find the disease-causing gene mutation. Since there are many types of genetic diseases and different effects on offspring, patients or relatives with genetic diseases should undergo genetic counseling when considering childbirth and make an ideal and wise choice with the guidance and help of a consulting physician.