Reference charts of fetal biometric parameters in a group of healthy Nigerian women with singleton pregnancies

Abstract

Background: Fetal biometric assessment is critical for optimal obstetric management as fetal growth abnormalities are associated with perinatal morbidity and mortality. We sought to ascertain normal third trimester fetal biometric parameters and develop growth charts in a Nigerian obstetric population. Methods: A third trimester cross-sectional assessment of fetal biometric parameters at 2-weekly intervals from 28 -36 weeks and thereafter, weekly to 41 weeks’ gestation. At each gestational age, 50 women were recruited and had ultrasound scan where fetal biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) were assessed and estimated fetal weight (EFW) calculated using Hadlock algorithm. SPSS version 20 was used to calculate the mean values and percentiles (5th, 10th, 50th, 90th, and 95th) for the parameters and corresponding reference charts developed using Microsoft Excel. Results: The mean values and ranges of BPD and HC respectively among preterm fetuses were 81.6 ±2.1 mm (68.4 – 95.5) and 29.3 ± 0.7 cm (24.6 – 33.7) while that of term fetuses were 94.0 ± 2.8 mm (82.9 – 101.0) and 33.5 ± 0.8 cm (31.8 – 35.8). Mean values and ranges of AC, FL and EFW for preterm fetuses were 29.1 ± 1.1 cm (23.3 – 35.4), 63.0 ± 1.9 mm (51.4 – 74.7), 2.1 ± 0.2 Kg (1.10 – 3.48). Mean values and ranges of AC, FL and EFW for fetuses at term were 35.2 ± 1.2 cm (32.7 – 41.3), 74.4 ± 1.9 mm (69.6 – 79.5) and 3.6 ± 0.3 Kg (3.02 – 4.85). Reference charts for normal fetal growth were derived from 28 – 41 weeks’ gestation. Conclusion: Reference third trimester fetal growth charts were established and are useful tools for clinical management in this obstetric population.