Association Between Increased Nuchal Translucency and Foetal CNS Abnormalities in Euploid Foetuses: Systematic Review and Meta-Analysis

Objective: Increased nuchal translucency (NT) thickness at 10–14 weeks’ gestation is a well-established marker of chromosomal abnormalities, foetal structural defects, genetic syndromes, and foetal death; however, its association with foetal central nervous system (CNS) abnormalities has not been systematically evaluated. This study aimed to review and synthesise existing evidence on the relationship between first-trimester increased NT and prenatal ultrasound–detected foetal CNS abnormalities. Methods: A systematic literature search of MEDLINE, Embase, and CINAHL was conducted in accordance with PRISMA guidelines and registered in PROSPERO. Studies reporting increased NT in singleton pregnancies and structural abnormalities of the foetal CNS identified on prenatal ultrasound were included. Study selection, data extraction, and quality assessment were performed independently by two reviewers. Results: Twenty-three studies, including 15,592 euploid pregnancies with increased NT, met the inclusion criteria. Definitions of increased NT varied across studies, most commonly >95th centile or ≥3.5 mm. The pooled prevalence of CNS anomalies was 1.16% (95% CI 0.68–1.95; I2 = 80%). In three comparative studies including 6040 pregnancies with increased NT and 152,682 with normal NT, increased NT was associated with higher odds of CNS anomalies (OR 3.22, 95% CI 1.52–6.80; I2 = 74.1%). Conclusions: These findings suggest that euploid foetuses with increased NT may have a higher risk of CNS abnormalities.