Table 4. Pregnancy complications and risk of preterm birth.

	Preterm group		Control group		P	OR	95%CI
	n	%	n	%
Placenta previa
No	1287	98.5	1315	99.8		1.000
Yes	19	1.5	3	0.2	0.002	9.500	2.213–40.784
Gestational Diabetes Mellitus
No	1323	95.6	1353	98.5		1.000
Yes	61	4.4	21	1.5	0.000	3.222	1.899–5.468
Hypertensive disorder complicating pregnancy
No	1242	89.3	1349	97.0		1.000
Yes	149	10.7	42	3.0	0.000	3.972	2.756–5.725