Table 1

 (B) Distribution of potential confounding factors among those included in the complete data analysis compared with those who were not included (all are singletons in the children in focus subgroup of ALSPAC)

VariableIncluded in complete data analysis*(Max N = 369)Excluded from complete data analysis(Max N = 1025)p†
NMeanSDNMeanSD
*Restricted to those with information on diet and confounders at all four ages. †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)36939.50.08102539.50.050.6
Mid-parental height (cm)‡369170.70.4573170.98.70.7
Categorical variables: N % N %
Maternal social class: % class I and II15542.028237.90.2
Paternal social class: % class I and II19853.737245.40.01
Maternal highest education: % degree7921.411411.9<0.001
Paternal highest education: % degree10227.617118.6<0.001
Birth order: % firstborn19352.343244.40.01