Objective: This study aimed to assess the prenatal and perinatal outcomes of fetuses with increased nuchal translucency (NT) and examine the relationship between NT thickness, chromosomal findings, and adverse pregnancy outcomes, such as fetal loss and neonatal morbidity.

Materials and Methods: This retrospective study included pregnant women referred to the perinatology clinic between February 2023 and July 2025 due to increased NT (≥3.0 mm) detected during first-trimester ultrasonography. Detailed ultrasonographic evaluation and invasive prenatal diagnostic testing were performed. Karyotyping and chromosomal microarray analysis (CMA) were conducted in all cases, and whole-exome sequencing (WES) was selectively applied.

Results: A total of 39 fetuses with increased NT were evaluated. The median NT value was 4.0 mm, and 35.9% of cases had NT values ≥4.5 mm, representing a high-risk subgroup. Chromosomal abnormalities were detected in 56.4% of fetuses, with trisomy 21 being the most common abnormality (35.9%). Additional ultrasonographic findings were observed in 64.1% of fetuses with a normal karyotype, among whom intrauterine fetal loss and neonatal morbidity rates were 15.4%. Chromosomal microarray analysis provided additional diagnostic yield beyond karyotyping. Whole-exome sequencing did not identify pathogenic variants; however, one case resulted in intrauterine fetal loss. These findings indicate that increased NT may be associated with adverse pregnancy outcomes even in the absence of detectable genetic abnormalities.

Conclusion: Increased NT is a strong predictive marker of chromosomal abnormalities, structural anomalies, and adverse neonatal outcomes, regardless of genetic test results. Chromosomal microarray analysis should be considered the minimum diagnostic standard, while advanced molecular testing, serial ultrasound follow-up, and comprehensive counselling may be beneficial in selected cases.