Pregnancy outcomes in patients with increased nuchal translucency using non-invasive prenatal testing and first trimester ultrasound.

BACKGROUND

Increased nuchal translucency (NT) during first-trimester ultrasound (US1) is linked to genetic and congenital abnormalities. However, its relevance in the era of non-invasive prenatal testing (NIPT) remains debated, and data on pregnancy outcomes in cases of increased NT with normal NIPT results are limited. The purpose of this study was to investigate the correlation between NT thickness and perinatal outcomes considering the results of NIPT and the findings of US1.

METHODS

A retrospective cohort study was conducted on fetuses with NT ≥ 2.5 mm detected during US1 from August 2017 to December 2023 at a Belgian referral center. Patients were categorized into four NT groups: 2.5-2.9 mm, 3-3.4 mm, 3.5-3.9 mm, and ≥4 mm. Data on NIPT, invasive genetic testing, ultrasound findings, and pregnancy outcomes were analyzed.

RESULTS

Among 490 patients, 432 (88.1 %) underwent NIPT, with 372 (86.1 %) receiving low-risk results. High-risk NIPT findings for trisomy 21 and 18 increased with NT (p < 0.001). Favorable perinatal outcomes decreased as NT increased, with 89.9 % healthy newborns when NT was <3.5 mm. In cases with ultrasound abnormalities, the probability of a healthy newborn declined from 96 % to 71 % (NT 2.5-3.4 mm). Trisomy 18, 13, and 21 were present in 2 % of cases with NT 2.5-3.4 mm and normal ultrasound findings.

CONCLUSION

A strongly significant relationship exists between NT measurements, and the results of NIPT/pregnancy outcomes. NIPT and ultrasound help guide counseling and management of cases with increased NT, notably between 2.5- and 3.4-mm.

IMPLICATION: The combination of first trimester ultrasound findings and the result of non-invasive prenatal testing is a valuable tool to counsel patients with increased nuchal translucency, notably between 2.5 and 3.4 mm.