TABLE 1.

Sample Characteristics by GA

	GA
	23–24 Weeks	25–26 Weeks	27 Weeks	n
Maternal characteristics
Age, y
<21	25	47	28	113
21–35	21	46	34	585
>35	18	43	38	175
Education
≤12 years (high school)	22	48	30	347
>12 and <16 years	27	36	37	198
≥16 years (college or higher)	16	46	38	303
Maternal IQ (z Score)
≤ −2	12	61	27	33
> −2 and ≤ −1	21	52	27	62
> −1 and ≤1	21	44	35	603
Single marital status
Yes	21	45	34	348
No	20	45	34	525
Public insurance
Yes	21	47	32	301
No	21	44	36	559
Racial identity
White	21	43	37	542
Black	22	51	27	226
Other	17	44	39	95
Hispanic
Yes	23	40	37	86
No	20	46	34	784
Newborn characteristics
Gender
Male	23	45	32	445
Female	18	46	36	428
Birth weight, g
≤750	50	37	13	323
751–1000	5	61	33	378
>1000	0	24	76	172
Birth weight z score
< −2	4	69	27	51
≥ −2 and < −1	18	45	37	116
≥ −1	22	44	34	706
Postnatal characteristics
Echolucent lesion
Yes	29	42	29	55
No	20	45	34	818
Ventriculomegaly
Yes	30	46	24	92
No	19	45	35	781
Necrotizing enterocolitis (Bell stage 3b)
Yes	33	57	10	30
No	20	45	35	843
Retinopathy of prematurity pre-threshold)
Yes	44	49	7	113
No	17	45	37	747
Bronchopulmonary dysplasia (oxygen at 36 weeks)
Yes	32	46	22	452
No	9	44	47	414
Maximum column N	180	395	298	873

Data are presented as percentages unless otherwise indicated. Maximum N = 873.