Table 1.

Univariate associations between antenatal factors and the risk of chronic lung disease (CLD). The right-most column provides the maximum number of infants with the attribute listed in each row; any differences are due to missing data. All other data are the percentage of infants with CLD among those infants with the attribute listed on the two left columns and the respiratory patterns listed as column headings. For example, among infants with a gestational age of 23–24 weeks who had the Low FiO2 respiratory pattern, the prevalence of CLD was 30%.

Antenatal factors		Respiratory Pattern			Row N
		Low FiO2	PD*	EPPD*
Gestational age (weeks)	23–24	30	76	85	250
	25–26	19	57	64	560
	27	15	33	62	394
Birth weight (g)	≤ 750	41	74	81	461
	751–1000	14	43	58	512
	> 1000	11	29	51	231
Birth weight Z-score	< −2	70	68	86	75
	≥ −2 to −1	38	70	80	163
	≥ −1	13	47	65	966
Sex	Male	18	56	69	638
	Female	16	47	69	566
Antenatal steroid	Complete	17	50	71	767
	Partial	16	56	67	316
	None	21	53	64	117
Number of fetuses	Single	18	53	69	819
	Multiple	16	50	69	385
Cesarean delivery	Yes	16	54	70	804
	No	24	48	68	400
Delivery indication	PTL	15	49	67	526
	pPROM*	12	52	67	265
	Preeclampsia	40	64	74	163
	Abruption	19	48	73	126
	Cervical Insufficiency	13	45	57	72
	Fetal indication	10	67	85	52
Percent CLD		17	52	69	52
Maximum Column N		240	456	508	1204

^*PD=pulmonary deterioration, EPPD=early and persistent lung dysfunction, pPROM=prolonged, premature rupture of membranes