Table VII.

Stepwise logistic regression analysis of the presence of cervical length <25 mm, amniotic fluid ‘sludge’ positive, or both as explanatory variables for the occurrence of spontaneous preterm delivery at <28 weeks, <32 weeks, and <35 weeks of gestation in asymptomatic high-risk patients at 14-24 weeks ultrasound

	OR (95% CI)	OR (95% CI)	OR (95% CI)
	CL <25 mm	AF ‘sludge’ positive	CL <25 mm + AF ‘sludge’ positive
Delivery <28 weeks	6.8 (1.2 – 39.5)	9.1 (2.9 – 28.6)	14.8 (3.9 – 56.5)
Delivery <32 weeks	6.1 (1.4 – 27.5)	6.2 (2.2 – 17.3)	9.9 (3 – 32.4)
Delivery <35 weeks	7.2 (1.8 – 28.3)	5.3 (2 – 14)	6.9 (2.3 – 20.5)

CL: cervical length; OR: odds ratio; CI: confidence interval.

Explanatory variables: sludge, cervical length <25 mm, gestational age at ultrasound, prior preterm delivery, vaginal bleeding, and cervical cerclage.