Abstract:
Fetal gestational age calculation has been found to be influenced by differences in race. Discrepancy has been noted on previous studies done on fetal neck circumference and area measurements which were attributed to racial difference. This study was aimed at correlating fetal neck circumference and area with common gestational age predictors in second and third trimesters and to determine whether there is racial difference between Nigerians and Caucasians. This prospective cross sectional study was done on 723 pregnant patients between 14-40 weeks of gestation selected using convenient sampling method at Braithwaite Memorial Specialist Hospital Portharcourt. Axial fetal neck circumference and area values were calculated as mean of three separate measurements. Other sonographic measurements includes biparietal diameter, femur length, abdominal circumference and head circumference. Mean fetal neck circumference and area values at 40 weeks gestation are 14.32±0.76cm and 15.55±1.68cm2 respectively. High values of Pearson correlation coefficient between fetal neck circumference and area and other biometric parameters signify strong correlation. Regression model equations relating FNC and FNA with other biometric parameters were generated as follows. FNC (cm) = 21.978 +0.065(FL) + 0.021(BPD) + 0.064(AC) + 0.259(HC). FNA (cm2) = -287.917+ -1.033(FL) – 1.600(BPD) + 3.159 (AC) + 2.687(HC). No statistical significant difference was noted in fetal neck circumference measurement between Nigerian and Caucasians (p <0.05) while there is statistical significant difference in fetal neck area measurement between Nigerians and Caucasians (p= 0.05) Nomograms generated can be used to determine gestational age in late pregnancy and rule out neck anomalies associated with neck size.
