Table 5.

Odds ratios (OR) and 95% confidence intervals (CI) for the association between four indicators of placental hemorrhage and spontaneous or medically indicated preterm delivery (PTD)

	PTD (n)	Unadjusted		Mutually Adjusted*		Adjusted for maternal characteristics†		Adjusted for maternal characteristics and hypertension‡
		OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI
Preterm Delivery, spontaneous§	169
Placental abruption	13	5.4	2.2, 13.2	4.3	1.7, 10.6	4.0	1.6, 10.1	3.9	1.5, 10.0
Disc-impacting Blood Clot	17	2.0	1.0, 3.8	1.5	0.8, 3.0	1.6	0.8, 3.1	1.7	0.9, 3.4
Microscopic Hemorrhage, top quintile	51	1.7	1.1, 2.5	1.6	1.0, 2.4	1.6	1.1, 2.5	1.6	1.1, 2.5
First Trimester Bleeding	44	1.6	1.1, 2.4	1.5	1.0, 2.3	1.6	1.0, 2.5	1.6	1.1, 2.5
Preterm Delivery, indicated§	69
Placental abruption	6	5.9	2.0, 18.1	4.1	1.3, 13.1	4.0	1.2, 13.9	3.0	0.6, 14.6
Disc-impacting Blood Clot	9	2.9	1.3, 6.6	2.2	0.9, 5.2	2.2	0.9, 5.3	1.1	0.4, 3.4
Microscopic Hemorrhage, top quintile	21	1.8	1.0, 3.2	1.6	0.9, 2.8	1.6	0.9, 3.0	1.7	0.8, 3.2
First Trimester Bleeding	22	2.0	1.2, 3.6	1.9	1.1, 3.4	2.1	1.2, 3.9	2.2	1.1, 4.3

^*Model includes all four types of evidence of placental hemorrhage

^†Model includes all four types of evidence of placental hemorrhage, maternal race, marital status, and BMI (categorical)

^‡Model includes all four types of evidence of placental hemorrhage, maternal race, marital status, BMI (categorical), and hypertension.

^§OR and 95% CI for both PTD subtypes calculated simultaneously using weighted polytomous logistic regression models.

NOTE: Boldface denotes P<0.05.