n = 6044≥4 drinks a day n = 1921 χ 2 (1 d.f.) p Prenatal factors Maternal age (≥35 years)10 %11 %1.560.211 Any smoking15 %30 %209.44<0.001 Cannabis use1 %4 %62.41<0.001 Other illicit drug use0.3 %0.8 %7.200.007 Parity (≥1)54 %61 %26.34<0.001 Highest maternal education (O level or above)73 %63 %77.18<0.001 Own home79 %70 %65.28<0.001 Married81 %71 %81.20<0.001 Maternal depression11 %18 %60.54<0.001Child factors Gestational age (≤36 weeks)4 %4 %0.060.802 Gender (male)51 %52 %0.780.377 Birth weight (kg)3.44 (0.52)3.44 (0.54) t = 0.11a 0.915% or mean(s.d.) a t test, t = 0.11 To check for possible selection bias we assessed whether the availability of outcome measures (SDQ and KS2 data) was associated with the exposure and other confounding variables (listed above). These assessments were made using χ 2 or t tests as appropriate.To assess for possible risk associated with background alcohol consumption at other times outside of pregnancy as opposed to the risk from exposure during pregnancy (intra-uterine exposure), we examined the univariable relationships between postnatal binge pattern of drinking (when the child was aged 5 years) and outcome measures.We formally tested for possible gender interaction within the unadjusted models and, where appropriate, regression analyses were repeated separately by gender.Three sets of sensitivity analyses
