Will the NT value at 13 weeks be higher than that at 11 weeks?

During the whole process of women's pregnancy, many examinations need to be carried out, which can detect abnormalities of the fetus as early as possible and take preventive measures in advance. For example, B-ultrasound, Down syndrome screening and NT value are all necessary examinations for women during pregnancy. So, will the NT value at 13 weeks be higher than that at 11 weeks?

If the NT value is checked at 13 weeks, it will be higher than at 11 weeks. The NT value test during a woman's pregnancy is usually carried out at 11-13 weeks. Since the fetus is in the growth and development period, if the test is done two weeks later, the NT value will naturally be higher.

As the fetus grows, the zona translucency behind the neck will increase and generally disappear by the 14th week of pregnancy. The standard value of fetal NT is around 3mm, but the test results will be affected by the fetal blood, resulting in some deviations. If the NT value test result exceeds 3mm, it is considered abnormal, and the higher the NT value, the greater the risk, and the pregnant woman needs further examination.

If the NT value reaches 6mm, the baby is likely to suffer from Down syndrome, or have abnormalities in the sex chromosomes, and sometimes have heart problems. Because the height of the NT value cannot completely determine whether the baby has symptoms, pregnant women must cooperate with doctors to conduct in-depth examinations, such as amniocentesis or DNA testing, to check whether the fetus is sick.

The NT value is high, what problems may exist in the fetus

1. Down syndrome baby

According to clinical experiment statistics, about 75% of babies with Down syndrome can be screened out through this method. The main reason is that the extracellular zona pellucida of the neck skin of babies with Down syndrome will increase, and a large amount of extracellular fluid will be absorbed within the zona pellucida, resulting in thickening of the neck zona pellucida. The main manifestations of Down syndrome baby deformity are: severe intellectual disability, inability to be independent in daily life, and accompanied by malformations of the reproductive organs, bones, digestive system, and heart.

2. Congenital heart malformation

The 10th to 14th week of pregnancy is a critical turning point for the gradual development and maturation of the fetal heart. If the fetus has congenital heart defects, its venous return system will be obstructed, causing the neck venous pressure to rise, the return of tissue fluid to be blocked, and then a large amount of fluid will accumulate in the neck, resulting in an increase in the thickness of the nuchal translucency.

3. Other functional malformations

The fetus's internal organs and tissues are basically formed around 12 weeks of pregnancy. Through NT examination, it is possible to basically screen whether the fetus has limb deformities, spinal deformities, etc.

4. Lymphatic hygroma

Because the fetus's neck lymph vessels and jugular sinus are interconnected around 11 to 14 weeks of pregnancy, a small amount of tissue fluid may accumulate in the neck during this period, resulting in temporary NT thickening, which will gradually dissipate after 14 weeks of pregnancy. If too much tissue fluid accumulates in the neck and does not dissipate for a long time, it may be lymphatic cystic hygroma.