The length of the NT examination is related to the baby’s position. The normal operation time is within 30 minutes, and if the baby’s position is suitable for observation, it may take 10 minutes to complete. In a few cases, the examination may take longer if the baby is not in a suitable position for observation and is not moving or sleeping, depending on the actual situation. If the fetal position is not correct and may affect the examination result, the pregnant woman can promote fetal movement through appropriate activities, such as walking or climbing stairs, so as to adjust the fetal position and obtain accurate examination results, which may prolong the examination time. It is easy to detect. After 14 weeks of gestation, the zona pellucida tends to disappear and this test may be missed, and only Down screening and 4D ultrasound can be used for screening. Pregnant women can also do proper exercise everyday, which can promote the growth and development of the fetus; it is recommended to stay away from toxic and harmful chemicals and drugs prohibited for pregnant women to avoid being detrimental to the growth of the fetus.