Advertisement

A Spatial Approach to Examining Individual and Disparity-Level Factors and Birth Outcomes

      Objective

      Investigate the contributions of Area Deprivation Index (ADI) and census block group to birthweight and SGA (< 10th percentile) using gestational sex and age-matched birth weight z-scores, and preterm birth (PTB) (< 37 weeks).

      Study Design

      A retrospective cohort study of Dane County, WI births (n=13,272) from 1/2016-6/2018 was used to explore effects of ADI (a ranked measure from 1-10 of neighborhood socioeconomic disadvantage at the census block group, modeled as a linear term) and census block group (modeled as a tensor product spline of centroids) on birthweight, SGA, PTB. Models adjusted for race/ethnicity, cigarette use, delivery route, pregnancy-related or chronic hypertension, pre-gestational and gestational diabetes, number of prenatal visits, maternal age, total weight gain, and pre-pregnancy.

      Results

      We find weak evidence of an association of ADI (standard deviation units) with birthweight z-score (-0.01, 95% CI: -0.03-0.01, p= 0.109 or SGA(1.06, 95% CI: 0.99-1.14, p=0.058). Birth weight z-score (p=0.006) and SGA (p=0.078) were associated with spatial location. Mean birth weight z-scores were lowest (-0.72) and SGA prevalence was highest (24.6%) in the urban center of Madison, while mean birth weight z-score was highest (0.18) and SGA prevalence was lowest (3.1%) in rural areas near the NE/SE/SW county borders. We find little evidence of associations of ADI (0.95, 95% CI: 0.86 – 1.04, p=0.27) or spatial location (p=0.27) with PTB. We find an effect of race/ethnicity on birth weight. Black (-0.67, 95%CI [-0.85,-0.49]) and Asian/PI (-0.62, 95% CI [-0.80,-0.45]) mothers were more likely to have low birth weight z-scores than White (-0.36, 95% CI [-0.53,-0.19]) and had higher probability of SGA (0.31, 95% CI [0.17,0.45] and 0.29, 95% CI [0.16,0.42]) than White (0.18, 95% CI [0.09,0.28]) mothers.

      Conclusion

      We identified geographic variations in birthweight and SGA at a granular level using census block groups and a holistic measure of deprivation, which can inform targeted public health interventions.
      Figure thumbnail fx1
      Figure thumbnail fx2