Can Down syndrome screening be done twice?

I believe that many people in life often go for Down syndrome screening. This screening work is of concern to many people, especially for some problems that have occurred in the family. Some Down syndrome screening is successfully recovered in one time. At this time, everyone will think of doing it a second time, but because the requirements for Down syndrome screening are relatively strict, whether a second examination can be done has become a matter of concern to many people in normal times.

Why can't Down syndrome screening be done twice?

necessity

Fetuses with Down syndrome are not exclusive to older pregnant women. Although older pregnant women over 35 years old are closely related to Down syndrome, the older the age, the greater the chance of giving birth to a child with Down syndrome. However, young women may also give birth to children with Down syndrome, and only 20% of Down syndrome

Down syndrome fetus

The syndrome occurs in older pregnant women, and the other 80% of Down syndrome babies are born to young pregnant women under 35 years old. Therefore, if only older pregnant women are examined, it will not be a good way to prevent Down syndrome.

On the other hand, if all pregnant women undergo amniocentesis or chorionic villus sampling, not only will the cost be higher, but it will also increase the chance of miscarriage, so it is not necessary for all women to undergo amniocentesis or chorionic villus sampling. Currently, the best way to prevent Down syndrome is: all young pregnant women undergo Down syndrome screening tests, and those who are shown to be at high risk will undergo amniocentesis or chorionic villus sampling. Through amniocentesis or chorionic villus sampling, it can be determined whether the fetal chromosomes are normal and whether the fetus has Down syndrome.

Check time

Young pregnant women under the age of 34 should undergo Down syndrome screening, which can be performed between 15 and 20 weeks of pregnancy, and preferably between 16 and 18 weeks. Pregnant women who are over 34 years old, women with Down syndrome in their family, and women who have given birth to children with Down syndrome are already at high risk, so they do not need to undergo Down syndrome screening and should go directly to amniocentesis or chorionic villus sampling.

Check for dangers

Down syndrome screening is a safe and convenient test that poses no risk to either the pregnant woman or the fetus. The test is done by testing the concentration of alpha-fetoprotein (AFP) and human chorionic gonadotropin (β-hCG) in the pregnant woman's blood, so the pregnant woman only needs to draw a little blood for the test and there is no danger.