Prenatal Diagnosis and Pregnancy Outcomes in Fetuses With Increased Nuchal Translucency Thickness.

OBJECTIVE

To evaluate prenatal diagnosis and pregnancy outcomes in fetuses with nuchal translucency (NT) thickening ≥ 95th percentile (P95).

METHODS

In total, 3328 singleton pregnancies diagnosed with increased NT thickness on first-trimester ultrasound screening were retrospectively included. In addition, second-trimester ultrasound, noninvasive prenatal testing, and follow-up data were collected.

RESULTS

There were 2815 patients with isolated fetal NT thickening (Group A) and 513 patients with fetal NT thickening combined with other abnormalities (Group B). The prenatal ultrasound diagnosis rate was 44.29%, and the prenatal ultrasound diagnosis concordance rate in Group B was greater than that in Group A (p < 0.001). The chromosomal abnormality rates in Groups A and B were 20.00% and 51.22%, respectively. Moreover, the incidence of chromosomal abnormalities in Group B was greater than that in Group A, and it increased with increasing NT thickness in Groups A and B (both p < 0.001). The most common chromosomal abnormality was Trisomy 21. In addition, the structural abnormalities and soft indicators observed on ultrasound included congenital heart disease and cystic hygroma. The live birth rates were 82.31% in Group A and 13.84% in Group B (p < 0.001). Furthermore, after the termination group was excluded, with increasing NT thickness, the live birth rate decreased, whereas the spontaneous abortion/embryo arrest rate increased (both p < 0.001). With respect to live births, NT thickness was negatively correlated (p < 0.05) in Groups A and B, and maternal age was positively correlated in Group A (p < 0.001).

CONCLUSIONS

NT thickening suggests a greater risk of chromosomal abnormalities (especially Trisomy 21), and this risk is even greater when it is accompanied by other abnormalities. Therefore, ultrasound and prenatal diagnosis are recommended. Pregnancy outcomes tend to be less favorable when NT thickening is accompanied by additional abnormalities, and a progressive increase in NT thickness is generally associated with a declining prognosis.