Table 4.

Crude and adjusted odds ratios for the association between variables and preterm birth (< 34 weeks)

	OR (95% CI)	p value	aOR (95% CI)	p value
Sepsis	13.57 (12.40–14.84)	< 0.001	11.69 (10.64–12.84)	< 0.001
Maternal age ≥ 35 years	1.81 (1.70–1.93)	< 0.001	1.73 (1.63–1.85)	< 0.001
Urbanisation
Urban	Ref		Ref
Rural	1.27 (1.19–1.36)	< 0.001	1.14 (1.07–1.22)	< 0.001
Low insured income a	1.35 (1.28–1.42)	< 0.001	1.30 (1.23–1.37)	< 0.001
Comorbidities
Hypertension	8.42 (6.49–10.93)	< 0.001	2.92 (2.11–4.05)	< 0.001
Hyperlipidemia	4.32 (3.20–5.82)	< 0.001	1.64 (1.12–2.40)	0.011
Diabetes mellitus	5.92 (4.46–7.88)	< 0.001	1.35 (0.93–1.96)	0.110
Malignancy	1.78 (1.15–2.76)	0.010	1.55 (0.99–2.44)	0.057
Depression	1.53 (1.09–2.14)	0.015	1.16 (0.81–1.65)	0.413
Hyperthyroidism	1.26 (0.92–1.73)	0.143	1.07 (0.77–1.50)	0.676
Chronic liver diseases	1.96 (1.36–2.81)	< 0.001	1.51 (1.03–2.22)	0.037
Connective tissue disease	2.50 (1.59–3.93)	< 0.001	1.61 (0.98–2.64)	0.062
Gestational risks
Gestational diabetes	0.98 (0.78–1.24)	0.881	0.65 (0.51–0.84)	0.001
History of preterm delivery	13.40 (9.59–18.74)	< 0.001	7.00 (4.71–10.41)	< 0.001
Current smoker	5.19 (3.43–7.84)	< 0.001	3.11 (1.94–4.99)	< 0.001
Cervical insufficiency	28.87 (19.79–42.12)	< 0.001	19.65 (12.86–30.05)	< 0.001
Preeclampsia	10.45 (9.10–12.00)	< 0.001	8.33 (7.17–9.68)	< 0.001

^aInsured income lower than median income (17,280 New Taiwan dollars)