Table 4.

Logistic Regressions for Mode of Delivery and Gestational Age at Delivery

	Unadjusted Model N=487		Adjusted Model N=468
	OR (95% CI)	P Value	OR (95% CI)	P Value
Cesarean delivery
Historical control	1.5 (1.0–2.2)	0.0259	1.8 (1.2–2.8)	0.004
Maternal age, y
21–34			1.2 (0.4–3.2)	0.6583
≥35			1.4 (0.5–3.8)
Site
Site 1			1.6 (0.9–3.0)	0.007
Site 2			3.4 (1.7–6.8)
Site 3			2.1 (1.1–3.9)
Site 5			1.7 (1.0–2.7)
Gestational age, <39 wk
Historical control	1.9 (1.3–2.8)	0.0011	2.1 (1.4–3.3)	0.0003
Maternal age, y
21–34			1.8 (0.7–4.8)	0.172
≥35			2.3 (0.8–6.4)
Site
Site 1			1.1 (0.6–2.0)	0.239
Site 2			1.7 (0.8–3.4)
Site 3			0.6 (0.3–1.2)
Site 5			0.9 (0.6–1.4)

OR indicates odds ratio.

Full model: adjusting for maternal age (referent: ≤20 years), and site (referent: Site 4).