Prenatal screening can also be called Down syndrome screening, but of course, in addition to assessing the risk of Down syndrome in the fetus, it can also assess the risk of trisomy 18 and open neural tube defects in the fetus. Since the risks and prognosis of Down syndrome, trisomy 18 and open neural tube defects are available on the website, I will not repeat them here. In summary: each of these affected children may be born to every couple with serious consequences. The following are a few areas that are often misunderstood by expectant mothers and fathers in outpatient consultations, and I hope to learn together, make progress together, and understand prenatal screening more clearly. Myth #1: Prenatal screening can be done at any gestational age, and you can go to the hospital whenever you want. Answer: Obviously, this is wrong, which also leads to some pregnant women miss prenatal screening time. The range of prenatal screening weeks in early pregnancy is 8 weeks-13 weeks and 6 days; the range of prenatal screening weeks in middle pregnancy is 15 weeks-20 weeks and 6 days. For pregnant women who have irregular menstrual cycles and cannot remember the time of their last menstrual period, they must follow the fetal ultrasound to calculate the gestational week. Myth 2: Prenatal screening is very powerful and can screen for any disease. Answer: The role of prenatal screening should not be overstated, it can only assess the risk of several diseases we have mentioned above. Prenatal screening in some medical units also increases the risk of trisomy 13. Prenatal screening does not screen for all diseases. Myth 3: Prenatal screening is accurate, mine is low risk, my baby will be fine. I’m going to be devastated and my fetus is not going to make it. Answer: Obviously, these are two extreme emotions, and the pregnant woman overstates the accuracy of the prenatal screening report. A well-managed, well-practiced prenatal screening laboratory has a screening detection rate of about 80-90%, although there are certainly laboratories that boast higher detection rates, but no laboratory can achieve a 100% detection rate. Therefore, screening for low risk only indicates that the risk of fetal disease is low, but there is still a possibility of missed screening. The vast majority of fetuses with high risk of screening are fine after prenatal diagnosis (chorionic villus aspiration, amniotic fluid aspiration, cord blood aspiration). Myth 4: Prenatal screening results are inaccurate, and it makes people nervous if a high-risk result comes out, so we don’t do it. Answer: This view is held by many pregnant women and their families, they believe that prenatal screening results are not accurate, especially the majority of high-risk screening results are false positives, pregnant women and their families fear, but also in the belly in vain to take a shot, so they will tell their friends around pregnant women do not do prenatal screening. Obviously, this “hindsight” view is very wrong. Let’s use a set of data as an example. There are about 550,000 live births in Yunnan Province each year, and based on a prevalence of Down’s syndrome of 1/1000, there will be 550 births of Down’s syndrome in Yunnan Province each year. Then we use the prenatal screening detection rate of 80% to calculate, each year through prenatal screening can avoid 440 cases of Down’s birth, and also avoid 440 families of misfortune, so the social significance of prenatal screening is undoubtedly. Myth 5: Fetal ultrasound can detect Down’s fetus, so there is no need to do prenatal screening. Answer: There is no doubt about the importance of fetal ultrasound, especially with the improvement of ultrasound doctors and the advanced ultrasound equipment, more and more abnormal fetuses are detected. However, some Down’s syndrome babies do not have typical morphological abnormalities on ultrasound images, so it is not uncommon to miss a Down’s syndrome baby on ultrasound. This is especially likely to happen in areas where the medical level is relatively backward and the ultrasonographer’s level needs to be improved. In fact, the most scientific method is: serological prenatal screening combined with fetal ultrasound (such as fetal NT measurement in early pregnancy, nasal bone measurement, jaw angle measurement, etc.) to maximize the detection rate of Down’s fetus. Myth 6: I am of advanced age (age >35 years), I want to go directly to the amniotic fluid for fetal chromosomal examination, so I will not do prenatal screening. Answer: In fact, there is nothing wrong with doing so. However, the information provided by the prenatal screening results is not simply the risk of Down’s syndrome. Especially for early prenatal screening, we can evaluate the function of the placenta based on the MoM values of free-βHCG (free beta subunit of human chorionic gonadotropin) and PAPP-A (pregnancy-associated protein A). If the MoM values of free-βHCG and PAPP-A are very, very low, then the risk of embryonic abortion is high. In mid-pregnancy prenatal screening, we can evaluate the risk of open neural tube defects based on the MoM of AFP (alpha-fetoprotein); we can evaluate the risk of gestational hypertension syndrome based on the MoM of Inhibin-A (inhibin A); in addition, there is a correlation between high free-betaHCG MoM and some adverse pregnancy outcomes ( For example, preterm delivery, intrauterine growth retardation, etc.). Therefore, we recommend prenatal screening at least once in early or mid-pregnancy for pregnant women of advanced age. Myth 7: Prenatal screening is as simple as drawing blood, and there is no need to accurately tell the hospital about the other information. Answer: Very wrong. The calculation of prenatal screening risk is based on the maternal age, height, weight, the exact gestational age of the fetus, personal history (whether or not to smoke, whether or not to have diabetes), reproductive history (whether or not to have had Down’s syndrome or other malformations), serum indicators (free-βHCG, PAPP-A, AFP, uE3, Inhibin-A) and other comprehensive assessment of the risk of the fetus. Therefore, only by providing detailed personal information can the objective accuracy of the maternal screening results be guaranteed and the false negative and false positive rates be minimized. Myth 8: A certain hospital can assess the risk of Down’s syndrome by doing two indicators, why do you have to do four, is it a disguised fee? Answer: The so-called use of several indicators, the technical term is called several screening. There are duplex (free-βHCG and AFP), triplex (free-βHCG, AFP and uE3), quadruplex (free-βHCG, AFP, uE3 and Inhibin-A), and the results of many studies at home and abroad prove that the protocol with the highest detection rate is quadruplex screening. Therefore, this is why most hospitals choose triple and quadruple. Myth 9: Now that non-invasive DNA technology is available and is quite accurate, I choose non-invasive DNA testing and don’t do prenatal screening. Answer: The exact name of non-invasive DNA technology is maternal blood fetal free DNA aneuploidy test, which is 99% accurate for trisomy 21, trisomy 18 and trisomy 13. However, due to the high cost of the test (around 2000-3000 RMB), it is a significant expense for many families, especially for economically underdeveloped areas like Yunnan, where it is not yet acceptable to every family. Therefore, at this stage, prenatal screening is still the most economical means of screening. In addition, the important information provided by prenatal screening is briefly listed in “Myth 6”, which cannot be replaced by non-invasive DNA technology. The consensus among many experts in the field of prenatal screening and prenatal diagnosis is that prenatal screening is preferred, and that maternal fetal free DNA aneuploidy testing is an option for pregnant women whose prenatal screening results are in the critical risk area, who have contraindications to prenatal diagnosis, or who refuse invasive prenatal diagnosis.