Abstract: Objective · To investigate the correlation between increased nuchal translucency (NT) thickness and fetal chromosomal abnormalities, severe structure anomalies and other abnormalities, and its value in assessment of fetal prognosis. Methods · Five hundred and eighty-three singleton fetuses with NT ≥ 2.5 mm in the first trimester (11-13+6 week) were retrospectively analyzed, of which 252 had invasive prenatal test for fetal chromosome and genetic tests. They were divided into 5 groups according to the NT thickness, 2.5～ 2.9 mm, 3.0～ 3.4 mm, 3.5～ 4.4 mm, and ≥ 4.5 mm as 1st to 4th group, and cystic hygroma as 5th group.The incidences among groups were analyzedCochran-Armitage Trend test. Fishers exact test was used to compare diversities of NT thickness among the major chromosomal abnormalities. Results · Among the 583 singleton fetuses, 59 were diagnosed as chromosomal abnormalities (23.4%, 59/252), 38 with structure anomalies (6.5%), of which 13 cases with severe cardiac anomalies (2.2%).There were 6 fetal demise, 3 ineviabortion, 2 stillborn, 94 terminations of pregnancy (8 for personal factors) and 478 live birth, without spontaneous abortions and congenital infections after invasive prenatal test. The differences among the incidences of chromosomal abnormalities, structure anomalies and cardiac anomalies in five groups were statistically significant (P0.000) and the incidences all increased with fetal NT thickness. The healthy living rates of fetus were 96.5%, 81.9%, 74.0%, 35.6%, and 6.7% among groups, respectively, and the incidences all decreased with fetal NT thickness (P0.000). Conclusion · Increased NT thickness is related to fetal chromosomal abnormalities, severe cardiac anomalies and poor pregnant outcome. The incidences of chromosomal abnormalities, structure anomalies, cardiac anomalies and pregnant outcome all increase with fetal NT thickness. In clinical practice, individualized guidance should be conducted according to different thickness of NT.

Key words: nuchal translucency, chromosomal abnormality, cardiac anomaly, prenatal diagnosis, ultrasound