Age, gender, and socioeconomic status (based on maternal education and net household income) did not differ between the groups.
For this reason the variables 'partner's weight'partnerner's height' and 'maternal social economic status based on maternal occupation' were excluded.
Based on maternal education attainment, the socioeconomic status distribution in the total group of eligible subjects was medium 60.1%, basic 33.0%, and superior 6.9%.
Where possible we matched the children for socioeconomic status (SES), based on maternal and paternal level of education (see, e.g., Bradley & Corwyn, 2002).
Child health status was based on maternal report (excellent, good, fair, poor, or terrible) and on change in the child's health compared to 1 year ago (about the same, better, or worse).
Socio-occupational status was grouped based on maternal education and job reported in the cohort or, if this information was missing, the corresponding paternal information.
Marital status and cohabitation were based on maternal self-report.
Demographic information based on maternal self-report collected in CPC studies included marital status, education, annual household income, ethnicity, and household composition.
Samples were matched based on maternal age, pre-pregnancy BMI, method of conception, ethnicity, smoking status, and infant sex.
Socioeconomic status (SES) was estimated by a validated 12-point socioeconomic score based on maternal education and paternal occupation and was classified into higher class (score 2 5), middle class (6 8) and lower class (9 12) [ 23].
