Which test measures the amount of fluid under the unborn baby's neck to assess the risk of Down's syndrome?

The Nuchal Translucency (NT) test is specifically designed to measure the amount of fluid that accumulates in the nuchal area, which is located at the back of an unborn baby's neck. This measurement is typically taken during the first trimester of pregnancy, usually between 11 and 14 weeks of gestation. An increased amount of fluid in this region can be an indicator of a higher risk for certain chromosomal conditions, including Down's syndrome.

This test is often combined with blood tests and carried out as part of a combined screening to provide a more comprehensive assessment of the risk of Down's syndrome and other genetic disorders. The NT measurement is essential for evaluating the risk, as higher levels of nuchal translucency are associated with potential developmental issues.

In contrast, the other tests listed serve different purposes: Alpha-Fetoprotein Screening is used to assess the risk of neural tube defects, the Glucose Tolerance Test measures how well the body processes sugar to screen for gestational diabetes, and the Beta hCG Test measures the levels of human chorionic gonadotropin hormone, which can indicate pregnancy or certain health issues but is not specific for assessing the risk of Down's syndrome.