RESUMEN
AIMS/HYPOTHESIS: To determine the impact of maternal diabetes during pregnancy on racial disparities in fetal growth. METHODS: Using linked birth certificate, inpatient hospital and prenatal claims data we examined live singleton births of mothers resident in South Carolina who self-reported their race as non-Hispanic white (NHW; n = 140,128) or non-Hispanic black (NHB; n = 82,492) and delivered at 28-42 weeks' gestation between 2004 and 2008. RESULTS: Prepregnancy diabetes prevalence was higher in NHB (3.0%) than in NHW (1.7%), while the prevalence of gestational diabetes mellitus (GDM) was similar in NHB (6.1%) and NHW (6.3%). At a delivery BMI of 35 kg/m(2), GDM exposure was associated with an average birthweight only 17 g (95% CI 4, 30) higher in NHW, but 78 g (95% CI 61, 95) higher in NHB (controlling for gestational age, maternal age, infant sex and availability of information on prenatal care). Figures for prepregnancy diabetes were 58 g (95% CI 34, 81) in NHW and 60 g (95% CI 37, 84) in NHB. GDM had a greater impact on birthweight in NHB than in NHW (60 g racial difference [95% CI 39, 82]), while prepregnancy diabetes had a large but similar impact. Similarly, the RR for GDM of having a large- relative to a normal-weight-for-gestational-age infant was lower in NHW (RR 1.41 [95% CI 1.34, 1.49]) than in NHB (RR 2.24 [95% CI 2.05, 2.46]). CONCLUSIONS/INTERPRETATION: These data suggest that the negative effects of GDM combined with obesity during pregnancy may be greater in NHB than in NHW individuals.