TABLE I.

Participant Demographics

Child Characteristics	N/Mean (SD/Percent), Median [Min, Max]
Gestational Age at Birth (weeks)	38.10 (1.77), 38.0 [35.29, 41]
Infants born preterm (<37 weeks)	126 (28.19%)
Birth Weight (grams)	2984.3 (581.20), 2974 [2225, 4659]
Stay in NICU	19 (4.25%)
Age at Neo MRI (weeks)	3.89 (2.15), 3.3 [1.71, 8.71]
Age at 1yr MRI (weeks)	55.81 (3.56), 5.14 [51.14, 62.71]
Age at 2yr MRI (weeks)	108.07 (4.47), 107.57 [99.0, 111.14]
Age at 1yr Mullen (weeks)	55.51 (3.35), 55.0 [49.71, 62.71]
Age at 2yr Mullen (weeks)	107.57 (3.80), 106.86 [99.0, 113.0]
1yr ELC	116.37 (12.88), 117 [78, 134]
2yr ELC	107.75 (15.51), 110 [71, 136]
Male / Female	240 (53.69%)
Female	207 (46.31%)
Single Gestation	211 (47.20%)
Twin Gestation	236 (52.80%)
Zygosity
Dizygotic Twins	137 (58.80%)
Monozygotic Twins	85 (36.48%)
Opposite Sex Twins	11 (4.72%)
Parental Characteristics *
Maternal Age (years)	30.23 (5.47), 30 [18, 40]
Paternal Age (years)	32.11 (5.96), 32 [19, 42]
Mother Education (years)	15.61 (3.37), 16 [8, 25]
Father Education (years)	15.19 (3.68), 16 [2, 26]
Total Household Income ($)	$74,128 ($55, 575), $68,000 [$3,120, $150,000]
Maternal / Paternal Race
White	339 (75.84%) / 319 (72.50%)
American Indian or Alaskan Native	2 (0.45%) / 0 (0%)
African American	95 (21.25%) / 103 (23.41%)
Asian	11 (2.46%) / 18 (4.09%)
Maternal / Paternal Ethnicity
Hispanic	50 (11.19%) / 58 (13.12%)
Non-Hispanic	397 (88.81%) / 384 (86.88%)

^*reported at the time of the child’s birth