TABLE 1

Distribution of Baseline Characteristics of the VLBW (<1500 g) and Term-born Groups

VariablenVLBW (n = 147)Term-born (n = 171)
Birth characteristics
    Birth weight, g318
        Mean ± SD1129 ± 2193596 ± 471a
        Range600 to 15002560 to 4930
    Gestational age, wk318
        Mean ± SD29.2 ± 2.240.1 ± 1.2a
        Range24.0 to 36.037.0 to 43.0
    Relative birth weight, z scoreb318
        Mean ± SD−1.3 ± 1.50.0 ± 1.0a
        Range−5.1 to 1.9−1.98 to 3.4
    Relative birth head circumference, z scoreb314
        Mean ± SD−1.1 ± 1.30.0 ± 0.9a
        Range−4.8 to 1.7−1.95 to 2.6
    Men, n (%)31862 (42.2)68 (39.8)
    Maternal preeclampsia, n (%)c31833 (22.4)13 (7.6)a
    Maternal smoking during pregnancy, n (%)30626 (18.7)27 (16.2)
    Cesarean delivery, n (%)31890 (61.2)20 (11.7)a
Perinatal risk factors in the VLBW group
    Days of mechanical ventilation, median (range)1445 (0 to 80)
    Bronchopulmonary dysplasia, n (%)14728 (19.0)
    Blood culture–verified sepsis in the neonatal period, n (%)1479 (6.1)
    Retinopathy of prematurity, n (%)1475 (3.4)
Adult characteristics
    Age at examination, y318
        Mean ± SD22.4 ± 2.122.5 ± 2.2
        Range18.5 to 27.018.5 to 27.1
    Head circumference, cm300
        Men
            Mean ± SD56.2 ± 1.757.1 ± 1.5a
            Range52.6 to 60.053.4 to 62.4
        Women
            Mean ± SD54.4 ± 1.555.5 ± 1.2a
            Range51.6 to 57.352.4 to 58.1
    School grade average in comprehensive school (scale 4–10)299
        Mean ± SD8.0 ± 0.88.2 ± 0.9d
        Range6.0 to 9.85.0 to 9.8
    Graduated from comprehensive school, n (%)315143 (99.3)171 (100)
    Helped by a special education teacher at school, n (%)30431 (22.6)20 (12.0)d
    Not right-handed, n (%)e31812 (8.2)15 (8.8)
    Parental educational attainment, n (%)f314
        I Elementary15 (10.4)11 (6.5)
        II High school35 (24.3)31 (18.2)
        III Intermediate53 (36.8)55 (32.4)
        IV University41 (28.5)73 (42.9)
  • T test was used for continuous variables, and χ2 test or Fischer's exact test was used for categorical variables.

  • a Significant at the <.001 level.

  • b Standardized birth measurements, based on Finnish growth chart.16 Gender and gestational age were accounted for.

  • c Defined according to current criteria.17

  • d Significant at the <.05 level.

  • e Including 13 participants (4 VLBW and 9 control) who reported “mixed” handedness.

  • f The highest level of education achieved by either parent.