TABLE 1

Frequency Characteristics for Control Variables

Categorical VariablenTypical Language Group, (N = 1280)Late-Talker Group, (N = 143)P
nMean (SD) or %nMean (SD) or %
Maternal age at conception, y1391125028.0214128.24 (6.12).67
Maternal life events during pregnancy, n events127711452.15 (1.96)1322.28 (2.15).46
Proportion of optimal birth weight1410126897.76 (12.75)14297.18 (13.1).61
Apgar scores 5 min after birth139112499 (0.72)1429.07 (0.67).28
Maternal education at pregnancy1394.37
    Completed secondary school54343.45639.4
    Did not complete secondary school70956.68660.6
Family income during pregnancy1326<.01
    ≥$24 00087273.27555.6
    <$24 00031926.86044.4
Biological father living with family during pregnancy1396.74
    Yes112489.612688.7
    No13010.41611.3
Smoking in pregnancy, cigarettes per d1397
    095676.210876.1.94
    1–51118.8107
    6–10766.196.3
    11–15584.674.9
    16–20362.964.2
    ≥21181.421.4
Alcohol consumption during pregnancy, per wk1397
    066352.87854.9.05
    ≤132025.53726.1
    2–621817.41712
    7–1038342.8
    ≥11161.364.2
Parity1397
    063750.84531.7<.01
    ≥161859.29768.3