Table 1.

Medical variables describing the preterm sample

Continuous Variables	Mean	SD	Minimum	Maximum
Birthweight (g)	1,080.8	247.0	600	1,467
Gestational age (weeks)	28.3	2.3	25	33
Apgar at 5 min	7.4	1.3	4	9
Days on supplemental oxygen	38.5	35.1	0	103
Days on mechanical ventilation	15.4	18.0	0	61
Days in hospital	71.6	27.6	30	128
Dichotomous variables	Negative history	Positive history	Comments
Retinopathy of prematurity	10	20	4 missing data
Bronchopulmonary dysplasia	19	15	Diagnosed at 28 days
Intraventricular hemorrhage	21	13	8 mild (grades 1–2); 5 severe (grades 3–4)
Periventricular leukomalacia	32	2