1.Pregnant women aged ≥ 35 years and husbands aged ≥ 55 years. 2, Couples with chromosomal abnormalities, such as chimerism, balance heterozygosity, inversion, etc. 3, Those who have a history of chromosomal abnormalities, such as trisomy 21, fragile X children, etc. 4.To determine the sex of the fetus and assist in the diagnosis of X-linked disease. 5.Suspected hematologic disorders, such as hemoglobinopathy. 6.Pregnant women with a history of unexplained miscarriage, stillbirth, stillbirth and malformed babies. 7, Pregnant women with a history of congenital metabolic diseases that can be diagnosed prenatally. 8.Pregnant women who are exposed to obvious teratogenic factors in early pregnancy, such as chemical substances, radiation or viral infection. 9.Other such as too much or too little amniotic fluid, intrauterine growth retardation, intrauterine hypoxia, etc.