Amniocentesis is a very common clinical prenatal test that can be performed to screen for other chromosomal disorders of Down’s syndrome, reducing the incidence of fetal chromosomal disorders to a certain extent. However, because amniocentesis is highly targeted and invasive, not all pregnant women need to have amniocentesis. So what is amniocentesis? The best time for amniocentesis is from 16 to 24 weeks, when there is relatively more amniotic fluid and a wider pool of amniotic fluid around the fetus, which is less likely to damage the fetus and will not cause miscarriage due to the sudden decrease in uterine pressure caused by the decrease in amniotic fluid, and when the proportion of viable cells in the amniotic fluid is the highest and the cell culture survival rate is the highest. However, there are risks associated with amniocentesis. Amniocentesis may cause infection, premature rupture of membranes, bleeding, and miscarriage. Since there are risks associated with amniocentesis, which pregnant women need to undergo amniocentesis? 1.Older pregnant women aged 35 and above; 2.Pregnant women with high risk of Down’s screening; 3.Previously had children with monogenic diseases, children with congenital chromosomal abnormalities, children with genetic metabolic diseases; 4.Parents or one of them has chromosomal abnormalities or carriers of chromosomal structural abnormalities; 5.Family history of Down’s syndrome, etc. 6.Pregnant women with multiple index abnormalities in ultrasound and need to undergo obstetric diagnosis. If there is obvious abdominal pain, vaginal flow and bleeding, fever and other symptoms after the operation, these are signs that the pregnant woman is in a dangerous situation, please go to the hospital for timely consultation.