570 DECLINING LOW BIRTH WEIGHT (LBW) IS ASSOCIATED WITH DECLINING SOCIODEMOGRAPHIC RISK

Abstract

Cross-sectional studies have shown numerous sociodemographic risk factors for LBW (<2500g). We studied changes over time in LBW rates and risk factors by analyzing two North Carolina birth cohorts a decade apart totaling over 350,000 births. Whites and non-whites showed nearly identical improvements in the percentage of deliveries < 36 weeks, but whites showed more improvement in LBW rates (mean 16% decline in LBW compared to 11% for non-whites). Maternal age and birth order distributions and educational attainments generally improved for both racial groups. Births to unwed mothers increased, however, especially among non-whites. Linear regression analysis of geographic- and race-specific sub-populations confirmed the association between 11 known risk factors and LBW for whites. Significant correlations existed for only 4 of the same factors for non-whites. We also found correlations between trends in 8 of the stronger risk factors and trends in LBW over time for whites; the only such association demonstrable for non-whites was with the change in fetal death ratio.

Conclusions: (1) LBW rates declined in N.C., 1968-1980, more for whites than non-whites; (2) declines over time in the known risk factors for LBW correlated with declines in LBW; (3) traditional risk factors for LBW are better predictors for whites than for non-whites, suggesting that these traditional indicators fail to capture important social, environmental or medical risks that continue to place non-whites at much higher risk for LBW.

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