First-trimester nasal bone length in a normal Latin American population
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Updated: Jun 27, 2026
Midface Hypoplasia and Cranial Base Morphology in Syndromic Craniosynostosis: A Comparative Analysis Study Using a Predictive Regression Model
Published on: November 4, 2025
Alexandra Casasbuenas1, Amy E Wong, Waldo Sepulveda
1Fetal Medicine Center, Department of Obstetrics and Gynecology, Clinica Las Condes, Santiago, Chile.
Objectives:
To report normative data of nasal bone length (NBL) in first-trimester singleton fetuses in a normal cohort of Latin American women.
Methods:
NBL was measured during routine first-trimester sonographic examination in 1040 singleton fetuses from an unselected population.
Results:
NBL increased linearly with advancing gestational age (GA) [NBL (mm) = - 1.10 + 0.03 x GA (days), R(2) = 0.21; p < 0.001]. Similarly, there was a linear relationship between the NBL and crown-lump length (CRL) [NBL (mm) = 0.41 + 0.02 x CRL (mm), R(2) = 0.27; p < 0.001]. The NBLs at the 50th percentile in our population were 1.5, 1.7, and 1.9 mm at 11, 12, and 13 weeks of gestation, respectively.
Conclusions:
Whereas categorizing a nasal bone as absent or present can be subjective because of variations in echogenicity due to technique and equipment, measurement of NBL is a more objective approach to nasal bone assessment in screening for aneuploidy. Measurement of NBL in the first trimester is feasible and can be easily obtained at the time of nuchal translucency assessment. The normative data we report can provide a reference for defining nasal bone hypoplasia in the first trimester in the Latin American population.
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