Regional variation in preterm birth and associated risk factors in Texas: A county level analysis using Geographic Information Systems

Background: Preterm birth (PTB) is a leading cause of neonatal mortality. We conducted a retrospective cross-sectional analysis of PTBs that occurred in Texas between 2008 and 2011 to characterize burden of PTB and its associated risk factors.

Methods: Vital statistics data was obtained from the Texas Department of State Health Services for the years 2008 through 2011. We used Geographic Information Systems (GIS) to locate areas most affected by PTB using zip code and census tracts. Socio-demographic and behavioral risk factor data were obtained from birth certificates. Analysis included singleton births for 379,141 women, and PTB was classified as <37 weeks gestational age. Multivariable logistic regression models were used to determine county-level contribution of maternal risk factors with PTB.

Results: The prevalence of PTB for the study population was 11.5%. African Americans exhibited higher prevalence, followed by Non Hispanic Whites, Other and Hispanics (15.5%, 11.6%, 10.4% and 10.1%, respectively). We also observed regional differences in PTB. Maternal age ≥35 (OR 1.32, 95% CI: 1.24-1.41), being African American(OR 1.22, 95% CI: 1.18-1.25), smoking in first trimester (OR 1.22, 95% CI: 1.11-1.36), previous PTB (OR 4.04, 95% CI: 3.78-4.31), pre-existing diabetes (OR 2.36, 95% CI: 2.13-2.60), gestational diabetes (OR 1.39, 95% CI: 1.33-1.46), pre-existing hypertension (OR 2.98, 95% CI: 2.77-3.20) and pregnancy-associated hypertension (OR 3.82, 95% CI: 3.69-3.95) were associated with increased risk of PTB.

Conclusion: The observed risk pattern identified across region, suggest potential differences in prenatal care, or exposure to specific risk factors during pregnancy.