Fetal growth curves for an ethnically diverse military population: The American Institute of Ultrasound in Medicine-accredited platform experience

Abstract

Objective: To determine which fetal growth curve provided the best estimates of fetal weight for a cohort of ethnically diverse patients at sea level. Methods: The study consisted of a population of 1,729 fetuses examined at sea level between January 1,1997, and June 30, 2000, at 18 weeks, 28 weeks, and term. Gestational age (GA) based on menstrual dates was confirmed or adjusted by crown-rump length or early second-trimester biometry. Fetal weight was estimated by using biparietal diameter, head circumference, abdominal circumference, and femur length. Our fetal growth curves were analyzed with fourth-order polynomial regression analysis, applying four previously defined formulae for fetal growth. Results: Fetal growth curves for estimated fetal weight demonstrated the expected parabolic shape, which varied according to the formulae used. Our curve best fit the following equation: estimated fetal weight = 4.522 - 0.22·GA age + 0.25-GA2 - 0.001·GA 3 + 5.248 × 10-6·GA4 (R 2 = 0.976). SD increased in concordance with GA. Conclusion: Madigan Army Medical Center serves a racially mixed, culturally diverse, military community with unrestricted access to prenatal care. Determination of the optimal population-appropriate growth curve at the correct GA assists clinicians in identifying fetuses at risk for growth restriction or macrosomia and therefore at risk for increased perinatal morbidity and death.