Table 1.

Population characteristics – Washington State preterm births 2002–2011 n = 56,537

Variable	Mother did not have chorioamnionitis % (95% CI)	Mother had chorioamnionitis % (95% CI)	p-value
Maternal Race			<0.001
Non-hispanic white	56.8 (53.4–57.2)	54.4 (52.5–56.3)
Non-hispanic black	4.3 (4.2–4.5)	6.5 (5.6–7.5)
Hispanic	17.5 (17.2–17.8)	15.8 (14.5–17.3)
Other/unknown	21.4 (21.0–21.7)	23.2 (21.6–24.8)
Infant Sex
Male	54.2 (53.7–54.6)	52.7 (50.7–54.7)
Female	45.8 (45.4–46.2)	47.3 (45.3–49.3)	0.16
Preterm premature rupture of membranes	19.7 (19.4–20.0)	45.8 (43.9–47.7)	<0.001
Small for gestational age (<10th percentile)	13.4 (13.1–13.7)	7.1 (6.2–8.2)	<0.001
Antenatal steroids	1.0 (0.9–1.0)	19.2 (17.6–20.9)	<0.001
Admission to neonatal intensive care unit	36.9 (36.4–37.3)	59.8 (57.7–61.8)	<0.001
Mechanical ventilation of the neonate	7.6 (7.3–7.8)	14.6 (13.3–16.0)	<0.001
Respiratory distress syndrome	11.3 (11.1–11.6)	25.1 (23.5–26.8)	<0.001
Bronchopulmonary dysplasia	1.5 (1.4–1.6)	7.7 (6.8–8.8)	<0.001
Stillbirth	3.2 (3.1–3.4)	4.7 (4.0–5.6)	<0.001
Infant Death	0.4 (0.3–0.4)	0.3 (0.2–0.7)	0.80
	Mean (Standard Deviation)	Mean (Standard Deviation)
Maternal age (years)	28.0 (6.3)	27.4 (6.4)	<0.001
Gestational age at delivery (weeks)	34.1 (2.9)	31.1 (4.5)	<0.001
Birth weight (grams)	2587.2 (1185.3)	2086.9 (1447.9)	<0.001