Objective     To investigate the normal range of the thickness of nuchal translucency (NT) in Tibetan fetuses in the single-fetus pregnant women living in the Qinghai plateau.  Methods      A total of 412 singleton pregnant Tibetan natives who undergoing NT test by ultrasonography in our hospital during October 2012 and December 2015 and living in Qinghai South Region (altitude more than 3 500 m) were subjected in this study. The pregnant women were at an age of 19 to 35 (25±2)

weighted 50 ~65 kg and had 11 ~13+ 6 weeks of gestational age. The fetal head hip length was ranged between 45 and 84 mm. After signed the informed content

the pregnant women were given prenatal ultrasound examination for the fetal structure and size

head hip length and NT thickness.  Results     The normal range of NT thickness (95%CI) was 1.1 ~3.1 mm in the Tibetan native women

and the median value was 2.1 mm.  Conclusion     Our results indicate that there is no difference in the NT thickness between the fetuses living in Tibetan plateau region and those living in plain area and of other nationalities.