Table 1.

Childhood socioeconomic exposure variables used to create the childhood SES index

Life-course variable	Survey question
Father's education level	The question was ‘What was the education level of your father when you were born?’ This was recoded as low education=1 (includes no education, informal education and primary) and high education level=0 (includes secondary and tertiary or high)
Mother's education level	Each respondent was asked ‘What was the education level of your mother when you were born?’ The codes were low education=1 (includes no education, informal education and primary) and high education level=0 (includes secondary and tertiary or high)
Father's occupation	State activity status and occupation of your father during your childhood. The variable was recoded as public sector=1, private sector=2, self-employed=3 and unemployed=4 (student, retired, homemaker)
Mother's occupation	State activity status and occupation of your mother during your childhood. The variable was recoded as public sector (government)=1, private sector (non-government)=2, self-employed=3 and unemployed=4 (student, retired, homemaker)
Stressful childhood	Has your life been stressful? Yes=1, no=0
Childhood diet	What kind of food was taken during childhood? Vegetarian=1, non-vegetarian=0
Perceived childhood health	How did you feel about your health? Below average=1, average=2 and above average=3
Childhood major ailment	Do you remember any major ailment you suffered? Yes=1 and no=2
Childhood SES	This was a resultant variable derived from the combination of material (socioeconomic) and psychosocial conditions in childhood (e.g. parental education, parental occupation, perceived childhood health and childhood diet). The positive and negative childhood socioeconomic experiences were grouped separately and an index was created to come up with three categories for childhood socioeconomic status: low=1, middle=2 and high=3 childhood SES

Source: Keetile et al.¹³