Can I do Down syndrome screening at 15 weeks?

Can I do Down syndrome screening at 15 weeks of pregnancy? During pregnancy checkups, doctors recommend that pregnant women undergo Down syndrome screening. However, many women today know nothing about Down syndrome screening, mainly because they lack professional knowledge about pregnancy. In fact, Down syndrome screening can determine whether the fetus has congenital IQ defects and the risk of Down syndrome.

Can I do Down syndrome screening at 15 weeks of pregnancy?

The timing of Down syndrome screening is also very critical. Generally, the Down syndrome screening we often talk about is carried out in the middle of pregnancy, but in recent years it can also be carried out in the early pregnancy. The time for Down syndrome screening in early pregnancy is 11 to 14 weeks, and the best time is 11 to 12 weeks. The main purpose of Down syndrome screening is to avoid the risk of congenital idiocy in the fetus to a certain extent.

Doctors recommend that the time for Down syndrome screening during mid-pregnancy is between 15 and 20 weeks of pregnancy, and the best time to check is between 16 and 18 weeks. Because whether it is early or late, it will affect the accuracy of the Down syndrome screening results. If during the screening process, the hospital's report clearly indicates a high-risk situation, the doctor will generally recommend amniocentesis. If a pregnant woman misses the time range for Down syndrome screening, there is no way to make up for it. She can only undergo amniocentesis and measure Down syndrome by drawing amniotic fluid.

How to judge the results of Down syndrome screening

The MOM that appears in the Down screening result sheet is the multiple of the median value, which refers to how many times the test result of the pregnant woman's individual blood cell markers is higher than the median blood cell marker concentration of all normal pregnant women at that week of pregnancy during prenatal diagnosis. The key data are alpha-fetoprotein (AFP), human chorionic gonadotropin (β-hCG), free estriol (uE3) and inhibin A.

1. The general range of alpha fetal protein (AFP) is 0.7-2.5MOM. If it is higher than 2.5MOM, it is high risk;

2. The higher the chorionic gonadotropin, the lower the free estriol (uE3) (generally ≤0.25MOM) and the higher the inhibin A (Inhibin A), the higher the chance that the fetus will suffer from Down syndrome.

The doctor will also enter the above four items together with the pregnant woman's age, weight, gestational age, etc. into the computer to estimate the risk factors for the baby to have Down syndrome. If the probability indicated by the test result exceeds the normal standard value (1/270), the result is positive, indicating that the probability of the fetus being sick is relatively high and more detailed examinations are needed. However, the calculation methods of each hospital's outpatient department are not exactly the same, and the standards are also different. Some hospitals' outpatient standard values ​​are lower than 1/270, while others are lower than 1/380.

Down syndrome screening test for male and female

At present, the only accurate way to identify the sex of the fetus is to use B-ultrasound to look at the fetal sexual organs or to do amniocentesis to test the sex chromosomes. Other methods are all medical certifications. In other words, Down syndrome screening is unreliable.