A study of genes encoding cytokines (IL6, IL10, TNF), cytokine receptors (IL6R, IL6ST), and glucocorticoid receptor (NR3C1) and susceptibility to bronchopulmonary dysplasia

Table 1 Clinical characteristics of the northern Finnish, Canadian, replication Finnish, and replication Hungarian preterm cohorts

	Northern Finnish		Canadian		Replication Finnish		Replication Hungarian
	BPD cases	Controls	BPD cases	Controls	BPD cases	Controls	BPD cases	Controls
n	56	197	58	68	39	188	29	40
Gestational age, weeks¹	27.5 ± 1.9 (24-30)	28.7 ± 1.7 (23-30)***	25.9 ± 1.6 (23-30)	27.6 ± 1.3 (24-30)***	26.5 ± 1.9 (24-30)	27.5 ± 2.0 (23-30)**	26.6 ± 1.8 (24-30)	28.6 ± 1.4 x 24-30)***
Gestational age <28 wk, n (%)	29 (51.8)	64 (32.5)**	48 (82.8)	32 (47.1)***	30 (76.9)	88 (46.8)**	19 (65.5)	6 (15.0)***
Birth weight, grams¹	938 ± 268 (495-1555)	1184 ± 313 (370-1850)***	834 ± 221 (385-1420)	1162 ± 243 (630-1900)***	878 ± 257 (440-1470)	1074 ± 308 (520-1970)***	928 ± 226 (510-1500)	1179 ± 193 (650-1500)***
Birth weight Z-score^1,2	-1.4 ± 1.41 (-4.5-1.8)	-0.9 ± 1.22 (-5.5-1.7)*	NA	NA	-1.4 ± 1.38 (-4.0-1.1)	-0.9 ± 1.3 (-4.0-2.6)	NA	NA
IUGR≤ -2 SD, n (%)	21 (37.5)	33 (16.8)**	11 (19.0)	3 (4.4)*	13 (33.3)	41 (21.8)	NA	NA
Male gender, n (%)	34 (60.7)	111 (56.3)	29 (50.0)	30 (44.1)	26 (66.7)	94 (50.0)	16 (55.2)	24 (60.0)
Singletons, n (%)	47 (83.9)	164 (83.2)	39 (67.2)	44 (64.7)	29 (74.4)	138 (73.4)	26 (89.7)	33 (82.5)
Severe BPD, n (%)	21 (37.5)		21 (36.2)		18 (46.2)		NA

*P <0.05, **P <0.01, ***P <0.001; Mann-Whitney U-test for continuous variables, X ²-test for dichotomous variables; ¹mean ± standard deviation (range); ²Birth weight Z-score describing fetal intrauterine growth. BPD cases were infants with moderate-to-severe BPD, and controls were infants with no-to-mild BPD. BPD, bronchopulmonary dysplasia; IUGR, intrauterine growth restriction; NA, information not available.