Impact of preterm birth on infant mortality for newborns with congenital heart defects: The EPICARD population-based cohort study

Table 3 Cox proportional hazard models of the impact of preterm birth on the risk of infant death

		HR	95% CI	p^c	HRa^d	95%CI	p^c
Isolated CHD^a
Gestational age (weeks)	28–31	6.5	2.6–16.3	<0.001	4.0	1.5–10.4	<0.001
	32–34	4.9	2.2–10.9		5.4	2.1–13.9
	35–36	1.1	0.4–3.1		0.9	0.3–2.7
Isolated major CHD^b
Gestational age (weeks)	28–31	3.3	1.3–8.4	0.003	2.1	0.8–5.4	0.045
	32–34	3.1	1.4–6.8		3.1	1.2–8.0
	35–36	0.8	0.3–2.1		0.6	0.2–1.9

^aIsolated CHD: excluding cases with chromosomal or other anomalies
^bIsolated major CHD: excluding cases with chromosomal or other anomalies and ventricular septal defects (VSD)
^cLikelihood ratio test
^dadjusted for maternal age, occupation, geographic origin, diabetes, intra-uterine growth restriction (IUGR) and multiple pregnancy

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