After non-invasive DNA suggests a chromosomal abnormality, amniocentesis can be performed to further determine it. Non-invasive DNA is mainly used to check the risk probability of the fetus suffering from trisomy 21, trisomy 18, and trisomy 13, so as to predict the risk of suffering from these three syndromes. However, after suggesting the presence of chromosomal abnormalities, it does not directly determine that there must be something wrong with the fetus and blindly make a decision to terminate the pregnancy; amniocentesis is also needed to further determine this. Amniocentesis is an invasive test that is usually performed in the middle to late stages of pregnancy. A part of the amniotic fluid is extracted from the amniotic cavity with a puncture needle, and the chromosomes are extracted from the amniotic fluid for chromosome karyotyping, and then a decision is made whether or not to continue the pregnancy based on the results of the amniocentesis, which can be obtained by consulting with a medical professional.