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Table 7 ORs of individual socio-demographic variables in model 5

From: Urban–rural disparity in the relationship between ambient air pollution and preterm birth

Variable

OR (95% CI)

Hubei

East

Middle

West

Minority (ref: Han)

1.04 (0.93–1.16)

0.99 (0.66–1.49)

1.26 (0.88–1.80)

0.95 (0.84–1.08)

Age (ref: 25–29)

 < 20

1.32 (1.18–1.48)*

1.20 (1.01–1.44)*

1.38 (1.13–1.69)*

1.51 (1.21–1.88)*

 20–24

0.97 (0.93–1.02)

0.93 (0.87–0.99)*

0.96 (0.89–1.04)

1.18 (1.06–1.33)*

 30–34

1.25 (1.19–1.32)*

1.17 (1.09–1.26)*

1.38 (1.26–1.50)*

1.33 (1.17–1.51)*

 ≥ 35

1.86 (1.75–1.98)*

1.84 (1.69–2.00)*

1.84 (1.64–2.07)*

1.94 (1.68–2.24)*

Education (ref: secondary)

 Elementary

0.97 (0.92–1.02)

0.94 (0.88–1.01)

0.96 (0.87–1.05)

1.08 (0.96–1.22)

 Tertiary

0.98 (0.91–1.06)

0.95 (0.87–1.05)

0.95 (0.80–1.14)

1.26 (1.01–1.59)*

 Regular health checks (ref: check < 5)

0.89 (0.83–0.95)*

0.84 (0.77–0.91)*

0.91 (0.78–1.08)

1.22 (0.95–1.56)

Firstborn (ref: non–firstborn)

1.04 (0.99–1.09)

0.98 (0.92–1.04)

1.22 (1.12–1.33)*

0.98 (0.89–1.09)

Female (ref: male)

0.79 (0.76–0.82)*

0.78 (0.74–0.82)*

0.79 (0.75–0.85)*

0.84 (0.77–0.92)*

Income

1.03 (0.96–1.10)

0.96 (0.86–1.08)

0.91 (0.77–1.07)

0.94 (0.57–1.52)

Income ^2

1.04 (1.01–1.07)*

1.02 (0.98–1.06)

1.65 (1.34–2.03)*

0.69 (0.52–0.93)*

  1. OR, odds ratio; CI, confidence interval
  2. Significant level: “*” p ≤ 0.05