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Table 3 Univariate and multivariate analyses of factors associated with preterm birth

From: Maternal preterm birth prediction in the United States: a case-control database study

Variables

Univariate

Multivariate

OR (95%CI)

P

OR (95%CI)

P

Age

 < 35 years

Ref

 

Ref

 

 ≥ 35 years

1.30 (1.28–1.32)

< 0.001

1.27 (1.26–1.29)

< 0.001

Race

 White

Ref

 

Ref

 

 Black

1.57 (1.55–1.59)

< 0.001

1.26 (1.23–1.29)

< 0.001

 Others

1.04 (1.02–1.06)

< 0.001

1.05 (1.03–1.07)

< 0.001

Education

 High school or below

Ref

 

Ref

 

 Bachelor

0.76 (0.75–0.77)

< 0.001

0.82 (0.81–0.84)

< 0.001

 Master or above

0.76 (0.74–0.77)

< 0.001

0.82 (0.81–0.83)

< 0.001

Age of spouse

 < 35 years

Ref

 

Ref

 

 ≥ 35 years

1.03 (1.02–1.04)

< 0.001

0.98 (0.97–0.99)

< 0.001

Race of spouse

 White

Ref

 

Ref

 

 Black

1.53 (1.51–1.55)

< 0.001

1.15 (1.12–1.18)

< 0.001

 Others

1.10 (1.08–1.11)

< 0.001

1.12 (1.10–1.14)

< 0.001

Education of spouse

 High school or below

Ref

 

Ref

 

 Bachelor

0.76 (0.75–0.77)

< 0.001

0.86 (0.84–0.87)

< 0.001

 Master or above

0.73 (0.71–0.74)

< 0.001

0.82 (0.80–0.84)

< 0.001

Pre-pregnancy BMI

 Normal

Ref

 

Ref

 

 Underweight

1.24 (1.21–1.28)

< 0.001

1.26 (1.22–1.30)

< 0.001

 Overweight

1.09 (1.08–1.11)

< 0.001

0.96 (0.95–0.98)

< 0.001

 Obesity

1.30 (1.29–1.32)

< 0.001

0.94 (0.93–0.96)

< 0.001

Prenatal care

 No

Ref

 

Ref

 

 Yes

0.48 (0.47–0.50)

< 0.001

0.48 (0.47–0.50)

< 0.001

Pregnancy smoking

 No

Ref

 

Ref

 

 Yes

1.42 (1.39–1.46)

< 0.001

1.27 (1.24–1.30)

< 0.001

Pre-pregnancy diabetes

 No

Ref

 

Ref

 

 Yes

2.78 (2.67–2.88)

< 0.001

2.08 (1.99–2.16)

< 0.001

Gestation diabetes

 No

Ref

 

Ref

 

 Yes

1.47 (1.44–1.49)

< 0.001

1.27 (1.24–1.29)

< 0.001

Pre-pregnancy hypertension

 No

Ref

 

Ref

 

 Yes

2.52 (2.45–2.59)

< 0.001

2.22 (2.16–2.29)

< 0.001

Gestation hypertension

 No

Ref

 

Ref

 

 Yes

2.61 (2.57–2.65)

< 0.001

2.49 (2.45–2.53)

< 0.001

Hypertension eclampsia

 No

Ref

 

Ref

 

 Yes

5.01 (4.70–5.35)

< 0.001

4.12 (3.83–4.42)

< 0.001

Previous preterm birth

 No

Ref

 

Ref

 

 Yes

3.43 (3.36–3.50)

< 0.001

2.95 (2.88–3.01)

< 0.001

Previous cesareans

 No

Ref

 

Ref

 

 Yes

1.29 (1.28–1.31)

< 0.001

1.13 (1.11–1.14)

< 0.001

Infections

 No

Ref

 

Ref

 

 Yes

1.30 (1.26–1.35)

< 0.001

1.12 (1.08–1.16)

< 0.001

Plurality

 No

Ref

 

Ref

 

 Yes

12.71 (12.47–12.95)

< 0.001

12.99 (12.73–13.24)

< 0.001