Table 1 Characteristics of the sample.
Characteristics, % (numerator/denominator) | N = 349 twin pairs |
|---|---|
Child | |
Gestational age, mean ± SD, weeks | 32 ± 3 |
Extremely preterm, <28 weeks | 11.75 (41/349) |
Very preterm, 28–31 weeks | 29.23 (102/349) |
Moderate/late preterm, 32–36 weeks | 59.03 (206/349) |
Birthweight discordance ≥400 g | 22.37 (66/295) |
Sex discordance | |
Male–male | 36.10 (126/349) |
Male–female | 22.92 (80/349) |
Female–female | 40.97 (143/349) |
Zygosity | |
Monozygotic | 41.83 (146/349) |
Dizygotic | 58.17 (206/349) |
Chronological age at assessment, mean ± SD, years | 7 ± 4 |
Maternal at childbirth | |
Maternal age, mean ± SD, years | 32 ± 4 |
Minority race/ethnicity | 6.98 (24/344) |
Low education [high school graduate or below] | 10.89 (38/349) |
Low family socioeconomic status [unemployed, unskilled, semi-skilled] | 8.60 (30/349) |
Single parent family | 4.30 (15/349) |
