Table 1.

Characteristics of 98 mothers with SPTB and 135 controls.

Parameters	SPTB	Controls	p Value
Mean maternal age (years)	30.20 ± 4.59	30.10 ± 3.92	0.28
Smoking during pregnancy % (n)	8.3 (8)	2.9 (4)	0.15
Previous SPTB % (n)	12.4 (12)	4.3 (6)	0.08
In vitro fertilization % (n)	4.1 (4)	1.4 (2)	0.31
Urogenital infections % (n)	7.2 (7)	4.3 (6)	0.35
High blood pressure % (n)	7.2 (7)	4.3 (6)	0.35
Stressful events during pregnancy % (n)	3.1 (3)	4.3 (6)	0.50

SPTB: spontaneous preterm birth.