Examining Disparities in Birth Outcomes Using Area Based Poverty Measures in a Large Metropolitan Area

BACKGROUND:  Disparities by race, ethnicity, socioeconomic status (SES), and other factors are commonly noted when examining birth outcomes, however most large public health datasets lack information about SES. The objectives of this study are to examine disparities in birth outcomes, including low birth weight (LBW), small for gestational age (SGA), and pre-term delivery (PTD) by SES using the poverty level of the census tract of maternal residence. In addition, we will assess the direction of disparities over time comparing results from 2000 and 2010.

METHODS:   We geocoded 2000 and 2010 birth records of all singleton births to women aged 15 to 55 who were residents of the Portland Metropolitan Area, the largest urban area in Oregon which includes Clackamas, Multnomah and Washington Counties. Geocoded records were linked to census tract poverty estimates from the 2000 Census and the 2010 American Communities Survey. We followed recommended cut points for census tract poverty levels: low- <5%, low-med- 5-<10%, med-high- 10-20%, high- >20% and used standard definitions for infant birth outcomes. LBW was defined as an infant weighing less than 2500 grams at birth; SGA was defined as an infant weighing below the 10th percentile for gestational age and PTD was defined as an infant born prior to 37 weeks gestation. We calculated bivariate risk ratios (RR) and 95% confidence intervals (CIs) for all outcomes comparing infants in high poverty census tracts to those in low poverty census tracts for both time periods. Additionally, we assessed the relationship between SES and birth outcomes for each racial/ethnic group.

RESULTS:  Results pending additional analysis

CONCLUSIONS:  Area based poverty measures of socioeconomic status can be meaningfully combined with public health datasets to identify and monitor health disparities in our communities.