Sonographic Assessment of Fetal Neck Circumference (NC) As a Predictor of Gestational Age

Abstract

Background The need for development of population based nomograms for ultrasound fetal dating cannot be overemphasised. The objective of this study was to develop a nomogram of Fetal Neck Circumference (NC) for predicting gestational age for this population.

Methods This was a cross sectional prospective study of 203 singleton normal pregnant women of 15–40 weeks’ gestation. Fetal NC was measured the 5th, 50th and 95th centile values were estimated at each week of gestational age, 50th centile values were then compared to Caucasian and African population study to assess variability.

Results A nomogram was derived and NC values showed no statistical significant difference compared to the Caucasians (p = 0.065, 0.257) and African (p = 0.947) population. There was a strong positive significant correlation (r² = 0.799; p = 0.001) between NC and average gestational age. Method of least square yielded to the equation y = 2.22x + 5.390. NC relationship with BPD (r² = 0.859; p = 0.001), FL (r² = 0.842; p = 0.001) and HC (r² = 0.662; p = 0.001) were also significant and positive. Estimated weekly increase in NC was 0.72 cm.

Conclusion This study derived nomogram for ultrasound measurement of fetal NC in a Northern Nigerian population. However, NC values from this study differ less with an African population than with Caucasian study population.

Keywords

Fetal neck circumference (NC) - Gestational age (GA) - Ultrasound - Nomogram