NT: Normal range
May 22, 2022
Source: Cainiu Health
Dr. Lv Aiming
Introduction
The nuchal translucency (NT) measurement should be less than 2.5–3 mm; values exceeding this range are considered high-risk. Between 11 weeks and 13 weeks + 6 days of gestation, all pregnant women should routinely undergo ultrasound examination to measure the NT—the thickness of the fetal nuchal translucency—with 2.5–3 mm serving as the cutoff value. Additional targeted ultrasound screening is recommended during the second trimester. If severe fetal structural anomalies are detected, termination of pregnancy may be indicated during the second trimester.
As is well known, Nuchal Translucency (NT) screening is a critically important prenatal test used to assess the risk of fetal congenital anomalies. So, what constitutes a normal NT measurement?
Normal NT Range
A normal NT value is less than 2.5–3 mm. Measurements exceeding this threshold are considered high-risk. Between 11 weeks and 13 weeks + 6 days of gestation, all pregnant women should routinely undergo ultrasound examination to measure the thickness of the fetal nuchal translucency—the fluid-filled space at the back of the fetal neck. A cutoff value of 2.5–3 mm is used clinically: values above this range correlate with an increased risk of chromosomal abnormalities (e.g., trisomy 21, 18, or 13) and structural fetal anomalies. Definitive diagnosis typically requires amniocentesis performed during the second trimester. If chromosomal abnormalities are confirmed via amniocentesis, termination of pregnancy during the second trimester may be recommended. Additionally, enhanced ultrasound screening should be conducted in the second trimester. Should severe structural anomalies be detected, second-trimester termination may also be indicated.
The optimal window for NT screening is between 11 weeks and 13 weeks + 6 days of gestation. Pregnant women must schedule this examination within this timeframe and follow up with appropriate clinical management based on results. The NT measurement reflects early embryonic development. If first- or second-trimester serum screening (e.g., combined or quadruple test) yields abnormal results, further diagnostic evaluation—including NT assessment—is strongly advised.
Pregnant women should engage in moderate physical activity daily to enhance overall health and prevent illness. Diet should be light yet nutritionally balanced, ensuring adequate intake of essential nutrients. We hope this information is helpful. Wishing you good health and happiness!
