The risk of having a chromosomally abnormal fetus is increased in older pregnancies, and there are state laws that require the provision of prenatal diagnosis. But at the same time, most of the older pregnant women are not easy to get pregnant, some of them got married very late, some of them were infertile for many years, and some of them went through a lot of trouble to get pregnant by IVF. They cherish their hard-earned fetus even more, and for some of them, it may be their last chance to have their own baby, so they are especially distressed when they face many choices of prenatal diagnosis and prenatal screening. Here I would like to introduce you to the pros and cons of several prenatal diagnostic and screening methods. The advantage of this procedure is that it can make prenatal diagnosis as early as possible, check the karyotype of all 23 pairs of chromosomes, and induce labor if fetal abnormalities are found, without waiting until the gestational age. The disadvantage is that there are not many hospitals in China that can perform this test, and it can lead to bleeding, infection, miscarriage and other adverse consequences that are slightly higher than amniocentesis, and requires an experienced doctor to perform it. Therefore, it is mostly used for early pregnancy screening for high-risk, thickened nuchal translucency (NT), fetuses with chromosomal abnormalities or other hereditary diseases delivered in the previous pregnancy, and elderly pregnant women who wish to know the condition of the fetus at an early stage. 2. Amniocentesis Amniocentesis, mostly known as amniocentesis, is usually performed at 16-22 weeks of gestation, also under ultrasound guidance, a fine needle puncture is performed to extract the fetal amniotic fluid, and then fetal cells are extracted from it for chromosome examination. The advantage is that the karyotype of all 23 pairs of chromosomes can be checked, resulting in low bleeding, infection, miscarriage and other adverse consequences, about 3 to 4 per 1,000, the disadvantage is that compared with the chorionic villus biopsy, the examination of the pregnancy week is larger, some pregnant women already have baby’s fetal movement, if the results suggest that there are fetal abnormalities, the induction of labor will be more painful. 3.Mid-trimester Down’s syndrome screening The indicators of the serum are drawn from pregnant women in the 15th to 22nd week of pregnancy, compared with the indicators of their corresponding gestational weeks, and the risk values of fetuses with trisomy 13, trisomy 18, trisomy 21 and neural tube defects are calculated by specific software, and determined to be “The aim of the screening is to detect high-risk or low-risk fetuses. The purpose of screening is to identify high-risk pregnancies for prenatal diagnosis. It has a certain rate of false positives (i.e., pregnant women carrying normal fetuses are at high risk) and false negatives (i.e., pregnant women carrying chromosomally abnormal fetuses are at low risk). In general, this method is able to detect about 60% to 70% of chromosomal abnormal fetuses, and about 1% to 2% of the high risk are chromosomal abnormal fetuses. Therefore, prenatal screening is not a substitute for prenatal diagnosis and requires the risk of false positives and false negatives. 4. Non-invasive genetic screening, also known as non-invasive DNA prenatal testing, is based on the principle of extracting fetal free DNA from a pregnant woman’s blood for testing and analysis to determine whether the fetus has chromosomal abnormalities, which usually include three chromosomal abnormalities: trisomy 21, trisomy 18 and trisomy 13. These three chromosomal abnormalities account for approximately 95% of autosomal aneuploidies, and the accuracy of this test is close to 100%, with a false positive rate (i.e., a pregnant woman with a normal fetus is at “high risk” for screening) of 0.5%. The advantage of this test is that it can be performed after 12 weeks of gestation, without invasive and invasive procedures, and allows for an early understanding of the fetus and more accurate results, but it is not the same as prenatal diagnosis. The disadvantages are that it is slightly more expensive, does not detect all chromosomal abnormalities, and positive results need to be confirmed by prenatal diagnosis. We would like to introduce the above four types of prenatal diagnosis and prenatal screening methods to pregnant women of advanced age. We sincerely hope that after you fully understand the effectiveness, risks, scope of application and significance of the results of these methods, you can make the right choice for yourself during early pregnancy according to your situation. Our doctors will respect your choice based on the principle of “informed consent”.