Social health inequalities emerge even before birth, with differences in prenatal monitoring and behaviour putting the unborn child at risk. Accordingly, 94% of women in managerial roles confirmed that they did not smoke during pregnancy, compared with 66% of women in manual work. Health inequalities develop from early childhood. At the age of 6, children from poor social backgrounds are more often overweight and this usually continues during childhood and adolescence.

Lifestyle, cultural and economic factors, and environmental exposure play a part in entrenching these health inequalities during childhood. Therefore, children from wealthy families eat a healthier diet, more often pursue an extra-curricular sports activity and spend less time on screens. In 2015, 8% of children of managers compared with 16% of children of manual workers in class CM2 spent at least two hours per day on a screen during the week. Poor families are less likely to seek preventive dental care and, in CM2 and in troisième (the third class), pupils in priority education are twice as likely as other pupils to have uncorrected problems with their distance vision (10% compared with 5% of those not in priority education in troisième in 2017).

Conversely, in late adolescence, the consumption of psychoactive substances, in particular of alcoholic beverages, is more common among those from wealthy backgrounds, except for daily smoking. At the age of 17, adolescents from wealthy families also consider themselves to be in good health more often than those from disadvantaged families.

Social health inequalities are already well-established at the start of adult life and will have a lifelong impact on health, notably due to the development of risk factors.