Is there an age limit for Down syndrome screening?

Nowadays, many mothers are older and they become pregnant very late. Therefore, they will be subject to many restrictions after reaching a certain age. For example, some examinations cannot be done, and the types of physical tests are different from those of normal people. Pregnant mothers are especially worried that they will develop Down syndrome due to their old age. In order to avoid this hereditary disease, they will go to the hospital for some examinations. However, considering the age limit, does Down syndrome screening exist? Is there an age limit for Down syndrome screening?

The best time for screening is between 15 and 20 weeks of pregnancy.

Preparation before the examination: There is no need to fast for Down syndrome screening, but it is related to the menstrual cycle, weight, height, accurate gestational age, and fetal age. It is best to consult a doctor for other preparations before the examination.

Down syndrome test

Detection of pregnancy through economical, simple and non-invasive testing method

Pregnant women at high risk of having certain congenital defects in order to further clarify the diagnosis and minimize the birth rate of abnormal fetuses. Prenatal screening usually refers to the detection of high-risk pregnant women carrying a fetus with congenital defects through the detection of maternal serum markers.

There are two periods for Down syndrome screening: the 9th to 13th week of pregnancy is called the early pregnancy screening, and the 14th to 21st week + 6 days of pregnancy is called the mid-pregnancy screening. Regardless of whether it is in the early or mid-term, pregnant women can generally get the screening results within one week after the blood test. If the result is high-risk, there is no need to panic because further examinations such as early chorionic villus sampling or mid-term amniocentesis are required to perform fetal chromosome karyotype analysis to confirm the diagnosis.

Syndrome

Children with Down syndrome have severe intellectual disabilities, congenital idiocy, tongue-throwing dementia, and are unable to take care of themselves. Some children also have complex cardiovascular diseases and require long-term care from their families, which places a great mental and financial burden on the families.

Who will give birth to a child with Down syndrome?

Down syndrome is a sporadic disease, so every pregnant woman has the possibility of giving birth to a child with Down syndrome. The chance of having a baby with Down syndrome increases with the age of the pregnant woman.

How to screen

Generally speaking, when doing Down syndrome screening, you must not eat or drink anything after 12 o'clock at night the day before the test, and come to the hospital on an empty stomach the next morning for the test. Fasting is not necessary. In addition, the examination is also related to the menstrual cycle, weight, height, accurate gestational age, and fetal age. It is best to consult a doctor for other preparations before the examination.

The screening includes drawing venous blood from pregnant women and ultrasound indicators (NT, nuchal translucent membrane thickness or alpha-fetoprotein AFP, human chorionic gonadotropin HCG, free estriol uE3 and inhibin A) and four mid-term indicators. The risk factor of "Down syndrome baby" is calculated based on the expected date of delivery, weight, age and gestational age of the pregnant woman at the time of blood sampling. In this way, more than 80% of Down syndrome babies can be detected with a false positive rate of 5%.

Prenatal screening

In the detection of multiple indicators of maternal serum prenatal screening, radioimmunoassay, enzyme immunoassay, time-resolved immunofluorescence and chemiluminescence methods are generally used. Since the results of radioimmunoassay and enzyme immunoassay vary greatly, time-resolved immunofluorescence and chemiluminescence methods are generally used.

Check time

The time is 9-13 weeks in the early stage of pregnancy, 14 weeks in the second stage of pregnancy, 21 weeks + 6 days, and it is best between 16 and 18 weeks.

Precautions

During prenatal screening, pregnant women need to provide more detailed personal information, including date of birth, last menstrual period, weight, whether they have insulin-dependent diabetes, whether they smoke, abnormal pregnancy history, etc. Because the risk rate statistics of screening need to be corrected according to the above factors, it is also very important to fill out the test form before blood is drawn.

Check the situation

MOM, or multiples of the median, refers to how many times the test result of an individual pregnant woman's serum marker in prenatal screening is the median concentration of the serum marker in the normal pregnant women group at that gestational week.