Amniocentesis cannot completely rule out fetal abnormalities. Amniocentesis is a procedure in which the doctor uses a thin puncture needle to pass through the abdominal wall, the myometrium and the amniotic membrane in order to extract about 20 ml of amniotic fluid, mainly to check the chromosomes of the fetus in it, monitored by ultrasound. The main purpose of the amniocentesis test is to identify the presence of chromosomal abnormalities in the fetus. Chromosomal abnormalities can lead to fetal malformations, with developmental abnormalities of the brain, nerves, heart, etc. However, the causes of fetal abnormalities are not only chromosomal, but also genetic, maternal, environmental and bi-parental genetic factors, so amniocentesis cannot completely rule out fetal abnormalities. Amniocentesis is only one of the methods to rule out fetal abnormalities. In addition, 4D ultrasound can observe the state of the fetus in the mother’s body and can make early diagnosis of fetal limb malformation and cardiovascular malformation. To prevent fetal malformation during pregnancy, pregnant women should increase nutrition, and it is recommended to eat foods rich in high quality protein, vitamins and high calcium, such as milk, green leafy vegetables and bean foods. In addition, pregnant women should also pay attention to rest, should not be overly tired, timely maternity checkups, and go to the hospital in time if they are found to be unwell.