Overview and Aims:

To investigate the association between fetal nuchal translucency (NT) thickness and perinatal and long-term neurodevelopmental outcomes in singleton euploid pregnancies, in the absence of chromosomal and structural anomalies or confirmed genetic syndromes.

Study design, Population and Methods:

Retrospective cohort study including 1648 pregnant women submitted to routine first-trimester screening in a portugueses central hospital between December 2014 and December 2015. Three groups were defined by NT thickness: NT<95th percentile, 212 cases - randomly selected in a 2:1 ratio to cases with increased NT; NT> 95th-99th percentile, 89 cases (5,4%); and NT>99th percentile, 16 cases (1,0%). Gestational and perinatal outcomes were compared in the three groups. Additionally, a screening tool for neurodevelopmental delay (Parent Report of Children’s Abilities - PARCA) was applied, with follow-up at a mean age of 2,0 years.

Results:

For children with a NT>99th percentile, there was a 7-fold increased risk of positive screening for neurodevelopmental delay (OR 6,80, 95% CI 0,03-0,65; 3 cases). For children with NT between the 95th and 99th percentile, the risk was also increased - about 3-fold (OR 2,9, 95% CI 0,12-0,94; 9 cases). Both results were compared with the group of children with NT<95th percentile (7 cases). No significant statistical differences were found between the groups regarding perinatal outcomes, except for fetal sex. The prevalence of fetuses with NT 95th-99th percentile was higher in males (59 cases, 66,3%), compared to fetuses with NT<95th percentile (106 cases, 56,7%).

Conclusions:

Among euploid fetuses with increased TN, there was an increased risk of positive screening for neurodevelopmental delay, particularly when NT>99th percentile. This does not represent a turning point in counselling, but alerts to the need for long-term follow-up of these children and the potential benefits of clinically assessing their neurodevelopment.

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