OP08.04: Fetal age assessment based on ultrasound in the second trimester and the effect of ethnic morphometric differences in Cameroon

Abstract

The African population is composed of a variety of ethnic groups, some of them very different. Some studies suggest that ethnic variation may influence dating. The aim of the present study was to establish reference values for fetal age assessment in Cameroon using two different ethnic groups (Fulani and Kirdi), and to determine the effect of maternal morphometry. This was a prospective cross-sectional study of 200 healthy pregnant women from Cameroon. The participants had regular menstrual periods and singleton uncomplicated pregnancies, and were recruited after informed consent. The head circumference (HC), outer-outer biparietal diameter (BPD) and femur length (FL) were measured using ultrasound at 12–22 weeks of gestation. Differences in demographic factors and fetal biometry between ethnic groups were assessed by t- and Chi-square tests. Compared to the Fulani women, Kirdi were 2 years older (P = 0.005), 3 cm taller (P = 0.001), 6 kg lighter (P < 0.0001), had higher ponderal index (P = 0.001), but were not different with regard to parity. There was no effect of weight (P = 0.20 (FL), 0.22 (HC), 0.39 (BPD)), height (P = 0.22 (FL), 0.58 (HC), 0.83 (BPD)), maternal age (P = 0.1 (BPD), 0.17 (FL), 0.34 (HC)), and BMI (P = 0.2 (HC), 0.33 (BPD), 0.6 (FL)) on fetal biometry. Compared with other relevant European charts we found them in agreement with charts from Norway (HC, BPD, FL) and England (HC, BPD); statistical analysis methods are similar in these three studies. The present study shows that ethnic differences had no significant effect on second-trimester fetal size. The current dating charts are in agreement with charts based on other populations and for all practical purposes applicable in a variety of populations, since ethnic differences hardly influence fetal biometry until after 22 weeks of gestation.