TABLE 2

Demographic Characteristics of the Participants at 24 Months

VariableAnalysis of CDI (N = 1720)aAnalysis of CSBS (N = 1680)b
Female gender, n (%)844 (49.1)824 (49.0)
Twin birth, n (%)43 (2.5)43 (2.6)
Preterm birth (<36 wk), n (%)49 (2.8)48 (2.9)
Birth weight, mean (SD), kg3.4 (0.5)3.4 (0.5)
Birth order, n (%)
    First child858 (50.1)838 (50.1)
    Second child603 (35.2)589 (35.2)
    Third child206 (12.0)204 (12.2)
    Fourth child39 (2.3)35 (2.1)
    Fifth child or more8 (0.5)8 (0.5)
Non-English-speaking background, n (%)101 (5.9)97 (5.8)
SEIFA disadvantage quintile, n (%)
    1st quintile (most disadvantaged)141 (8.2)138 (8.2)
    2nd quintile139 (8.1)135 (8.0)
    3rd quintile456 (26.5)448 (26.7)
    4th quintile659 (38.3)641 (38.2)
    5th quintile (least disadvantaged)324 (18.8)317 (18.9)
Family history of speech/language difficulties, n (%)424 (24.7)419 (24.9)
Maternal mental health problem indicated, n (%)522 (31.6)513 (31.6)
Maternal vocabulary score, mean (SD)27.6 (5.0)27.7 (5.0)
Maternal education level, n (%)
    ≤12 y370 (21.8)358 (21.6)
    13 y682 (40.2)666 (40.2)
    University degree407 (24.0)398 (24.0)
    Postgraduate qualification239 (14.1)236 (14.2)
Maternal age at birth of child, mean (SD), y31.3 (4.5)31.3 (4.4)
  • a Children were included in CDI analysis when aged between 23.5 and 25.5 months at the 24-month follow-up. Denominators in the column range from 1653 to 1720.

  • b Children were included in CSBS analysis when aged between 23.5 and 25 months at the 24-month follow-up; these children were also included in analyses of CDI. Denominators in the column range from 1621 to 1680.