Mid-Second Trimester Measurement of Nasal Bone Length in North Indian Population

Our objective for this study was to establish a reference range of normal fetal nasal bone length (NBL) from 14 to 22 weeks in a North Indian population.

Pregnant women with gestational age (GA) from 14 to 22 weeks undergoing ultrasonography with a single live fetus and no complications in the fetus or mother were selected for the study. The fetal nasal bone was measured in 2060 pregnant women from 2014 to 2018. The measurement was done by the double operator method; three measurements were taken for each woman when her fetus was in the midsagittal plane, and the nasal bone was located between a 45 and 135° angle to the ultrasound beam. We performed follow-up evaluations of all neonates.

The rate of growth of the fetal nasal bone during different weeks of gestation is described by an equation where NBL =0.365×GA+ 2.5885, with a fit estimate of R² = 0.97, P < 0.001. The median NBL increased with GA from 2.9 mm at 14 weeks to 5.8 mm at 22 weeks in a linear relationship. Our results in the North Indian population are similar to those in the South Indian population and differ from those in Chinese and Japanese populations.

The NBL in North Indian fetuses at 14-26 weeks of GA has a linear relationship to the week of gestation.