The contribution of childhood and adult socioeconomic position to adult obesity and smoking behaviour: an international comparison

Background our objective was to investigate the contribution of childhood and adult socioeconomic position (SEP) to adult obesity and smoking behaviour, in particular to establish the role of childhood circumstances across different studies in Europe and the US. Methods Seven population-based surveys in six Western countries (Britain, Denmark, Finland, Netherlands, Sweden, US) were examined, with participants aged 30-50 yr and born between 1910 and 1960. Adult smoking was analysed using three outcomes (ever, current, or ex-) and adult obesity was defined as body mass index (kg/m(2)) >= 30. Results A strong effect of adult social position was observed for smoking outcomes and obesity. For example, manual SEP in adulthood increased the risk of ever smoking (adjusted odds ratio (OR) 1.47-2.00 for men; 0.94-1.81 for women), and obesity (adjusted OR 1.06-2.24 for men, 1.21-3.26 for women). In most studies, childhood position was not associated with ever-smoking. For current smoking, manual childhood position was associated among women (adjusted OR 1.09-1.54), but no consistent pattern was seen for men. For ex-smoking, manual childhood origins lowered the chance of quitting among women (adjusted OR 0.64-0.81) except in the US (OR = 1.17); among men this association was seen in fewer studies (adjusted OR 0.74-1.09). For obesity, manual origins increased the risk for women (adjusted OR 0.96-2.50); effects were weaker among men but mostly in the same direction (adjusted OR 0.79-1.42). Conclusions As expected, adult SEP was an important influence on smoking behaviour and obesity. In addition, factors related to disadvantaged social origins appeared to increase the risk of obesity and reduce the probability of quitting smoking in adulthood, particularly in women.