Table 1

Demographic characteristics, substance use and risky sexual behaviour in late and early adolescence in both cohorts

Analyses of later adolescent substance use and multiple sexual partnersAnalyses of earlier adolescent substance use and early sexual initiation
Mean age (SD)1987/1990 (‘earlier’) cohort1999/2003 (‘later’) cohortMean age (SD)1987/1990 (‘earlier’) cohort1999/2003 (‘later’) cohort
18 years 7 months (3.9 months)19 years 3 months (6.4 months)15 years 8 months (3.8 months)15 years 5 months (3.7 months)
 Male41847.145449.9 Male41647.047350.7
 Female46952.945650.1 Female46853.046049.3
Social classSocial class
 Non-manual37842.641045.1 Non-manual37542.440843.8
 Manual50957.449954.9 Manual50957.652556.2
Current smoker*Started smoking at age <14*
 Yes29833.630833.9 Yes19321.919520.9
 No58966.460266.1 No69178.173879.1
Excessive drinking*Monthly drinking at age 15
 Yes18120.429532.4 Yes17519.860064.3
 No70679.661567.6 No70980.233335.7
Ever used illicit drugs*Ever illicit drugs at age 15
 Yes28832.553258.5 Yes859.639141.9
 No59967.537841.5 No79990.454258.1
3+ sexual partners*Sex at age <16*
 Yes21223.945349.8 Yes13915.726528.4
 No67576.145650.2 No74584.366871.6
  • * Information obtained during interview at age 18–19.

  • Defined as ≥22 units in the past week for boys, ≥15 units for girls.

  • Information obtained during interview at age 15 (earlier cohort) or self-completion questionnaire (later cohort).