Down syndrome screening risk

During pregnancy, women often undergo Down syndrome tests to prevent newborn screening. After the test, people are very worried that their children may have Down syndrome. The test process needs to be analyzed. So what is the normal risk of Down syndrome?

What is the normal risk of Down syndrome?

The critical point of Down syndrome risk rate is 1/270. If it exceeds this point, it is high risk, and if it is lower than this point, it is low risk. The risk rate of Down syndrome is 1/41174, which is less than (1/250), which is considered low risk. The risk of neural tube defects is 7.28 (index value 2.5). A value above 2.5 is considered high risk. The maternal age risk rate is 1/1018, which is low risk. The probability of having children with Down syndrome varies for parents of different ages, and it also depends on whether there are similar genetic diseases in the family. At present, Down syndrome screening will provide a risk rate based on comprehensive analysis of age, tests, etc.

High risk of Down syndrome means that after Down syndrome screening, the risk of conceiving a baby with Down syndrome is relatively high. Because the high risk of Down syndrome is only a risk estimated based on maternal blood test and the age and weight of the pregnant woman. Therefore, a fetus with a high risk of Down syndrome is not necessarily a baby with Down syndrome.

Down syndrome screening is generally based on the concentrations of alpha-fetoprotein (AFP) and beta-human gonadotropin (β-HCG) in the pregnant mother's blood cells, the test results of free estriol, combined with the pregnant woman's age, weight, maternal history and weeks of pregnancy, to calculate the relative risk factor of the disease. The result is a risk value, such as 1:2000, which means that there is a one in 2000 chance of suffering from the disease. Depending on the system selected, the parameters entered into the analysis are slightly different. Some software also includes the thickness of the collagen fibers in the fetal neck into the calculation, so the reference risk of each part is different.