Table 6. Risk factors for preterm birth.

Related factors	β	Waldχ2	P	OR	95%CI
Unmarried	1.074	2.504	0.114	2.926	0.774–11.059
Community	−0.505	8.590	0.003	0.603	0.430–0.846
Pre-pregnancy BMI (kg/m2)		8.175	0.043
<18.5	0.087	0.360	0.549	1.091	0.821–1.448
25–29.9	0.273	3.397	0.065	1.313	0.983–1.755
≥30.0	1.108	5.181	0.023	3.030	1.166–7.869
Balanced diet	−0.629	27.227	0.000	0.533	0.421–0.675
Prenatal care	−1.343	15.415	0.000	0.261	0.134–0.510
Stressful life events	1.711	14.807	0.000	5.535	2.315–13.231
Sex	0.515	14.068	0.000	1.674	1.279–2.191
Placenta previa	2.608	9.404	0.002	13.577	2.563–71.912
Home/office decorating	0.578	2.370	0.124	1.7783	0.854–3.722
Gestational diabetes mellitus	1.236	11.679	0.001	3.441	1.694–6.991
Hypertensive disorder complicating pregnancy	1.797	37.771	0.000	6.034	3.401–10.704
History of preterm birth	3.039	7.929	0.005	20.888	2.519–173.218
Reproductive abnormality	1.115	3.911	0.048	3.049	1.010–9.206