Table 1

 (A) Distribution of potential confounding factors among those included in basic models compared with those who were not included (all are singletons in the children in focus subgroup of ALSPAC)

VariableIncluded in basic models*(Max N = 1278)Excluded from basic models(Max N = 116)p†
*Restricted to those with information on age, sex, birth weight, and dietary intake at each age. †p Value obtained from t tests (continuous variables) or χ2 tests (categorical variables). ‡Mid-parental height was calculated as the average of maternal and paternal height.
Continuous variables
Gestational age (weeks)127839.50.0511639.40.20.4
Mid-parental height (cm)‡898170.80.344171.71.40.5
Categorical variables N % N %
Maternal social class: % class I and II41339.62433.40.3
Paternal social class: % class I and II54148.72937.70.6
Maternal highest education: % degree18214.71112.00.5
Paternal highest education: % degree25921.61416.10.2
Birth order: % firstborn57946.64646.00.9