Abstract 1511

Purpose: 1) To determine if the changes in perinatal health care (e.g., improved access, increased knowledge of nutrition and early intervention for problems that impact fetal well-being) that have occurred over the last 3 decades have led to changes in intrauterine growth. 2) To evaluate the effect of race and gender on intrauterine growth as measured by admission weight, length, and head circumference in a large population sample. Methods: Pediatrix Medical Group uses an electronic database system for daily medical record documentation. During the past 2 years, data from over 16,000 patients has been collected into this system. Data including birth weights, length and head circumference, estimated gestational age (EGA), gender and race (Afro-American, Caucasian, Hispanic) were available on 15,341 neonates. We compared the gestation-specific birth weights from this sample to those reported by Usher et al in 1969. We also evaluated the effect of race and gender on EGA-specific birth weight, length and head circumference using a multivariate analysis of variance. We evaluated EGA-specific differences using a Fisher's LSD multiple comparison test. Results: The sample included 6,831 female and 8,510 male neonates; there were 2,935 Afro-American, 2,485 Hispanic, and 8,292 Caucasian neonates. Gestational age had the largest influence on each birth parameter and there was a significant increase for each week increase in EGA. Growth curves generated from our data were nearly identical to those reported in 1969 for neonates between 32-40 weeks. Both race and gender had gestational age independent effects on all birth parameters. At each specific week of gestation, female neonates had lower average birth parameters than male neonates. We found significant differences between 32-40 weeks EGA. Racial comparisons showed that black neonates were disproportionately represented in the lower EGA groups. From 33-40 weeks EGA, Afro-American neonates were consistently shorter and of lower birth weight than Hispanic and Caucasian infants. Conclusions: Intrauterine growth patterns have not changed since Usher's original description in 1969. Our large sample has identified significant differences in growth patterns related to race and gender. However, the differences are small and not clinically relevant; therefore, a single set of growth curves is applicable across race and gender.