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Table 2 Bivariate and multivariate logistic regression estimation of odds of term infant mortality by contextual county characteristics and individual maternal sociodemographic, health and obstetric characteristics in the US, 2013

From: Poverty, urban-rural classification and term infant mortality: a population-based multilevel analysis

  Model 1 Model 2 Model 3 Model 4
Bivariate County variables Individual variables County + individual variables
OR 95%CI aOR 95%CI aOR 95%CI aOR 95%CI
Contextual County Characteristics
 Poverty
  Low Referent Referent   Referent
  Medium 1.41*** (1.19, 1.66) 1.39** (1.17, 1.64) 1.16 (0.99, 1.36)
  High 1.84*** (1.56, 2.18) 1.90*** (1.60, 2.27) 1.31*** (1.11, 1.54)
 County Urban/Rural Scheme
  Large central metro 1.07 (0.93, 1.22) 0.85* (0.75, 0.96) 0.98 (0.9, 1.1)
  Large fringe metro Referent Referent   Referent
  Medium metro 1.30*** (1.18, 1.46) 1.02 (0.91, 1.15) 1.05 (0.95, 1.17)
  Small metro 1.23*** (1.08, 1.41) 0.97 (0.84, 1.10) 0.95 (0.83, 1.08)
  Micropolitan (non-metro) metro 1.55*** (1.37, 1.76) 1.19** (1.04, 1.35) 1.10 (0.97, 1.24)
  Non-core (non-metro) 1.72*** (1.51, 1.97) 1.31*** (1.14, 1.50) 1.16* (1.02, 1.33)
Maternal Individual Characteristics
 Gestational age (weeks)
  37 2.30*** (2.13, 2.48) 2.12*** (1.95, 2.31) 2.12*** (1.95, 2.31)
  38 1.43*** (1.33, 1.53) 1.38*** (1.28,1.49) 1.38*** (1.28, 1.49)
  39 Referent   Referent Referent
  40 0.82*** (0.76, 0.88) 0.85*** (0.78, 0.92) 0.86*** (0.79, 0.93)
   ≥ 41 0.86** (0.77, 0.96) 0.92 (0.81, 1.04) 0.93 (0.82, 1.05)
 Maternal age (years)
  15–19 1.62*** (1.48, 1.77) 1.50*** (1.34, 1.68) 1.47*** (1.31, 1.65)
  20–24 1.39*** (1.30, 1.48) 1.19*** (1.10, 1.29) 1.18*** (1.09, 1.27)
  25–29 Referent   Referent Referent
  30–34 0.74*** (0.69, 0.80) 0.78*** (0.71, 0.85) 0.79*** (0.72, 0.86)
  35–39 0.76*** (0.69, 0.84) 0.83*** (0.74, 0.92) 0.84** (0.75, 0.94)
   ≥ 40 1.25** (1.08, 1.44) 1.29** (1.10, 1.52) 1.33** (1.12, 1.56)
 Maternal education
  High school or less 2.47*** (2.31, 2.65) 1.30*** (1.18, 1.44) 1.27*** (1.15, 1.40)
  Some college/AA 1.81*** (1.68, 1.96) 1.19*** (1.08, 1.31) 1.17** (1.06, 1.28)
  Bachelor’s or more Referent   Referent Referent
 Maternal race/ethnicity       
  Non-Hispanic White Referent   Referent Referent
  Non-Hispanic Black 1.63*** (1.53, 1.74) 1.19*** (1.10, 1.29) 1.20*** (1.11, 1.31)
  Hispanic 0.84*** (0.78, 0.89) 0.68*** (0.62, 0.73) 0.68*** (0.63, 0.74)
  Non-Hispanic Other 0.75*** (0.67, 0.84) 0.87* (0.76, 0.99) 0.89 (0.78, 1.01)
 Marital status
  No Referent   Referent Referent
  Yes 0.53*** (0.51, 0.56) 0.83*** (0.78, 0.89) 0.83*** (0.78, 0.89)
 Number of previous live births
  0 Referent   Referent Referent
  1–2 1.22*** (1.15, 1.29) 1.32*** (1.24, 1.42) 1.31*** (1.23, 1.41)
   ≥ 3 1.83*** (1.70, 1.97) 1.81*** (1.65, 2.00) 1.78*** (1.61, 1.96)
 Infant sex
  Male Referent   Referent Referent
  Female 0.84*** (0.80, 0.88) 0.84*** (0.80, 0.89) 0.84*** (0.80, 0.89)
 Month prenatal care began
  First trimester Referent   Referent Referent
  Second trimester 1.55*** (1.46, 1.65) 1.25*** (1.16, 1.34) 1.24*** (1.16, 1.33)
  Third trimester 2.23*** (2.04, 2.44) 1.71*** (1.55, 1.90) 1.70*** (1.54, 1.89)
  No prenatal care 3.71*** (3.25, 4.23) 2.12*** (1.80, 2.53) 2.09*** (1.76, 2.49)
 Tobacco use during pregnancy
  No Referent   Referent Referent
  Yes 2.59*** (2.43, 2.76) 1.79*** (1.65, 1.94) 1.77*** (1.63, 1.91)
 Chronic hypertension
  No Referent   Referent Referent
  Yes 1.64*** (1.38, 1.94) 1.32** (1.07, 1.62) 1.30* (1.06, 1.60)
 Chronic diabetes
  No Referent   Referent Referent
  Yes 1.06 (0.95, 1.18) 1.02 (0.90, 1.15) 1.02 (0 .90, 1.15)
 Pregnancy associated hypertension
  No Referent   Referent Referent
  Yes 1.18** (1.05, 1.32) 1.04 (0.91, 1.19) 1.03 (0.90, 1.18)
 Medicaid
  No Referent   Referent Referent
  Yes 1.95*** (1.85, 2.06) 1.20*** (1.11, 1.28) 1.18*** (1.10, 1.27)
N 2,551,828 2,551,828 2,551,828
ICC 0.015*** 0.006***
  1. * p < 0.05, ** p < 0.01, *** p < 0.001, low poverty (< 10%), medium poverty (10.0–19.9%), high poverty (≥20%)