Fetal congenital malformations are morphological defects of an organ or a part of the body due to intrinsic abnormal development, also known as birth defects. Humans have a high rate of birth defects, with a foreign incidence rate of about 15 percent. The domestic incidence rate is about l3.07‰. Birth defects occur in the following order: anencephaly, hydrocephalus, open spina bifida, cerebrospinal bulge, cleft lip, cleft palate, congenital heart disease, trisomy 21, abdominal bifida, and encephalocele. Fetal development is divided into embryonic cell stage, embryonic stage and fetal stage. Because of the different sensitivities of each stage to the effects of teratogenic factors, the outcome varies. Embryonic cell stage is relatively insensitive, teratogenic factors can lead to the death of embryonic cells, abortion; embryonic stage is the most sensitive, teratogenic factors can lead to abnormal fetal structural development; fetal stage teratogenic factors are only manifested in abnormal cell growth or death, rarely occur in fetal structural malformations. There are 3 types of factors that cause fetal malformations: 1. Environmental factors include drugs, chemicals, narcotics, and other substances that are accessible in the environment. Environmental factors teratogenicity and its dose effect, critical role and individual sensitivity absorption, metabolism, placental transit, the degree of exposure and so on. 2, viral infections TORCH this group of microbial infections have common characteristics, which can cause mother and child infection. Pregnant women due to endocrine changes and decreased immunity prone to primary infection, previously infected pregnant women in the body of the potential virus is also easy to be activated and recurrent infection. When viremia occurs in pregnant women, the virus can spread through the placenta or the birth canal to infect the fetus, causing preterm labor, miscarriage, stillbirth or teratology, as well as causing damage to multiple systems and organs in newborns, resulting in varying degrees of mental retardation and other symptoms. Especially in the first trimester of pregnancy, when the embryo is in the period of organ formation, viral infection at this time can destroy cells or inhibit cell division and value-added. Infection with the virus after the organ-forming stage can destroy tissues and organ structures, and can form a persistent infection that continues to be detoxified after birth and can cause corresponding lesions. Solid TORCH infection affects the quality of the population, and eugenics has an important relationship. 3, genetic factors chromosome number or structural abnormalities and sex chromosome abnormalities can lead to fetal malformations. Some defects are related to gender, such as pyloric obstruction, the mother suffers from this disease, the risk of its offspring than the father suffers from this disease when the risk is high. 4, a combination of factors polygenic inheritance and environmental factors can often lead to congenital heart disease, neural tube defects, cleft lip, cleft palate and pyloric obstruction and other fetal malformations, mostly occurring in female fetuses. Common fetal malformations 1, neural tube defects. Caused by a combination of factors, teratogenic factors act in the early embryonic stage, resulting in neural tube closure defects. The incidence of regional differences, the northern region of China up to 6‰ ~ 7% 0, accounting for 40% ~ 50% of the total number of fetal malformations, while the incidence of the southern region is only l‰ or so. Neural tube defects include common anencephaly, occipital cleft, dew brain and cranio-vertebral bifida. About 80% of neural tube defects are associated with hydrocephalus. (1) Anencephalic babies: the skull and brain tissue are missing, and brain tissue remnants are occasionally seen, often accompanied by adrenal hypoplasia and amniotic fluid excess. About 75% die during labor and delivery, while others die in the hours or days after delivery. On abdominal examination the fetus is mostly in the breech or face position with a small head. In cephalic presentation, vaginal examination may reveal an uneven cranial base, which should not be mistaken for a normal breech.The cranium is not visualized on B-mode ultrasonography, and a fetal head without a cranium is seen on abdominal radiography. Maternal serum alpha-fetoprotein is elevated. Anencephalic babies have an absent cranial appearance, bulging eyes, and a short neck. Once the diagnosis is confirmed. Labor should be induced as early as possible, and vaginal delivery is not difficult. If there is difficulty in delivering the fetal shoulder, wait or perform fetal destruction. (2) Spina bifida: part of the spinal canal is not completely closed, and the defect is mostly on the posterior side; occult spina bifida is a defect of the lumbosacral spinal canal, with skin covering the surface. The spinal cord and spinal nerves are normal, with no neurological symptoms; if there is a vertebral defect that causes the spinal cord and spinal membrane to protrude, the skin on the surface is wrapped in a cystic shape, which is called spinal spondylolisthesis, and there are often neurological symptoms. In the high prevalence of this disease, or have a history of spina bifida delivery of pregnant women should be prenatal screening, in the mid-pregnancy detection of maternal serum alpha-fetoprotein, B-type ultrasonography can be found in part of the spine two rows of strong echoes of the spacing of the spinal column becomes wider, spinal column is short, discontinuous, irregular, or irregular cystic material bulging. In severe cases, pregnancy should be terminated. This disease occurs ~ the risk of reoccurrence of 2% to 5%, the risk of two reoccurrences can be up to l0%, such as caused by environmental factors such as folic acid deficiency, folic acid supplementation can significantly reduce the incidence rate, it is advisable to start intervention in the third month before pregnancy. (3) Hydrocephalus: the cerebrospinal fluid reflux is blocked due to the failure of the cerebral aqueduct, and a large amount of cerebrospinal fluid is accumulated inside and outside the ventricles, which leads to the elevation of cranial pressure, dilation of the ventricles, increase of cranial cavity volume, widening of the cranial sutures, and increase of fontanel size. Abdominal palpation may reveal a wide fetal head. In case of cephalic preeclampsia, prenatal examination of the fetal head is positive for the trans-shame sign, vaginal examination of the preeclampsia is high, cranial sutures are wide, fontanelle is large and tense, and the bone is thin, soft, and elastic. B-mode ultrasonography after 20 weeks of gestation helps in diagnosis. Labor is induced immediately after diagnosis, and delivery is done vaginally after craniotomy. 2.Cleft lip and cleft lip and palate. The incidence rate is l‰, and the risk of recurrence is 4%. If the father is a patient, the incidence rate of offspring is 3%, and if the mother is a patient, the incidence rate of offspring is l4%. The palatal plate is intact in cleft lip, and in cleft lip and palate there is incomplete growth of the nose and teeth. Severe cleft palate may pass into the pharynx, severely affecting breastfeeding. Prenatal diagnosis is difficult, B-type ultrasound can only detect obvious cleft lip and palate, although fetoscopy can diagnose directly, but the damage is larger. Plastic correction in the neonatal period is more effective. 3, the joint twins for monozygotic twins unique malformation. b-type ultrasound examination can help diagnosis. After diagnosis, pregnancy should be terminated as soon as possible, and it is advisable to destroy the fetus vaginally. In the case of full-term pregnancy, the uterus should be delivered at term. For high-risk pregnant women with a history of adverse environmental exposure or a family history of malformation, prenatal screening should be performed, combined with laboratory tests and various instrumental tests for diagnosis. New diagnostic techniques and methods in recent years have the advantages of being early, rapid, accurate, and non-invasive. Utilizing these methods to monitor high-risk pregnant women, timely and accurate diagnosis can be made. 1 commonly used clinical diagnostic methods and techniques (1) ultrasound technology because of its easy application and non-traumatic has been used in clinical diagnosis, and can improve the safety and success rate of amniocentesis, cordocentesis and chorionic villus aspiration, so as to successfully carry out biochemical and genetic examinations; in recent years, three-dimensional ultrasound can assist in the diagnosis of fetal anomalies; (2) fetoscopy, embryoscopy, although belonging to the invasive diagnostic techniques, but can be more intuitive, accurate observation of the fetus, and can be more accurate. Although fetoscopy and embryoscopy are traumatic diagnostic techniques, they can observe the condition of fetus or embryo more intuitively and accurately, and they can sample the contents of the uterine cavity for diagnosis and even carry out intrauterine treatment. (3) Serologic testing for TORCH and other pathogenic microbial infections, pregnant women’s serum AFP, acetylcholinesterase testing can also screen for congenital malformations. (4) Amniocentesis, cordocentesis and chorionic villus aspiration (5) Biochemical tests HCG , AFP 2 Combined application of flow cytometry and monoclonal antibody technology The search for cells of fetal origin from the peripheral blood of pregnant women, followed by the use of polymerase chain reaction technology for genetic diagnosis has been successful and is in line with the development trend of prenatal diagnosis. Prevention and treatment Prevention of birth defects The principle of three-level prevention should be implemented, namely, removing the cause of disease, early diagnosis, and prolonging life. Establishing and improving perinatal health care, widely publicizing eugenic knowledge to the society, avoiding consanguineous marriages or marriages of patients with serious genetic diseases, and at the same time advocating age-appropriate childbearing, strengthening genetic counselling and prenatal diagnosis, paying attention to environmental protection, and reducing the hazards of all kinds of environmental teratogens can effectively reduce the birth rate of all kinds of congenitally malformed children. For congenital malformations that have no possibility of survival, such as anencephaly and hydrocephalus, once diagnosed, labor should be induced to terminate the pregnancy, with the principle that the mother should be free from damage, and if there are difficulties in delivery, the fetus can be destroyed if necessary; for congenital malformations that have a chance of survival and can be corrected through surgery, they should be delivered through the vagina as far as possible.