Table 4. Sensitivity analyses showing odds ratio (OR) for confirmed NEC in infants exposed to feeding advancements and PRBC transfusion 24 and 72 hours prior to NEC onset.

	Hazard Period	A	B	C	D	OR (95% CI) a
Feed fortification	24 hours	2	7	6	17	1.17 (0.39, 3.47)
	72 hours	6	12	8	6	1.50 (0.61, 3.67)
Feeding volume increase	24 hours	9	7	13	25	0.54 (0.21, 1.35)
	72 hours	32	8	11	3	0.73 (0.29, 1.81)
PRBC transfusion	24 hours	0	7	6	25	1.17 (0.39, 3.47)
	72 hours	3	12	5	18	2.40 (0.85, 6.81)

Abbreviations: NEC, necrotizing enterocolitis; PRBC, packed red blood cells

A: Number of concordant pairs exposed in both hazard and control period (n₁₁)

B: Number of discordant pairs exposed in hazard period, unexposed in control period (n₁₀)

C: Number of discordant pairs unexposed in hazard period, exposed in control period (n₀₁)

D: Number of concordant pairs unexposed in both hazard and control period (n₀₀)

^a OR defined as B/C or n₁₀/ n₀₁