An NT test is required in the third trimester and the most appropriate time for NT is between 11-13 weeks of pregnancy. The cost of an NT is around$200-300, which varies from hospital to hospital and is only an approximate cost. The NT is to measure the thickness of the zona pellucida at the back of the neck. If the thickness is abnormal, it means that there is a problem with the baby’s development and further examination is needed, but if the thickness is normal, you can continue to observe. In addition, the NT is also important for the calculation of the pregnancy week. Some women’s menstruation is not particularly accurate and it is not good to estimate the due date, so they can also use this NT test to re-account for the due date, which is more accurate.