Child physical development in the UK: the imprint of time and socioeconomic status

- Studies to date have not taken a unified approach to describe changes in inequalities in physical outcomes across childhood.
- We explore the existence and evolution of inequalities in multiple physical development outcomes as children grow older.
- Social inequalities are found for BMI (for females), overweight and body fat (for both genders) on average in childhood.
- Inequalities in weight, BMI, overweight and body fat significantly strengthen across childhood.
- Policies tackling socioeconomic inequalities need to take this trajectory into account.

ObjectivesSocial health inequalities remain a key policy challenge. The existing literature has not presented a synthetic view on the evolution of inequalities in physical development across childhood. We examine social disparities as children grow older using a range of different outcomes.Study designPopulation-based secondary data analysis.MethodsWe employ longitudinal data on British children aged 9 months to 12 years from the Millennium Cohort Study (n = 13,811-18,987) and focus on multiple child physical measures: weight, body mass index (BMI), overweight, fat mass and waist circumference.ResultsHigher family income is associated with lower BMI (for females), less body fat and a smaller likelihood of overweight (for both genders) on average throughout childhood. When income is multiplied by 3, the probability of overweight decreases by 2.8 (95% CI −0.041 to −0.016) percentage points for females and by 2.7 (95% CI −0.038 to −0.016) percentage points for males. Social inequalities in weight, BMI, overweight and body fat significantly widen as children grow older, for both genders. For instance, for females, when income is multiplied by 3, the probability of overweight decreases by 1.6 (95% CI −0.032 to −0.000) percentage points at ages 2-3 years, but by 8.6 (95% CI −0.112 to −0.060) percentage points at ages 10-12 years.ConclusionsThe trajectory of social inequalities, which may reflect the cumulative effect of family socioeconomic status, is a precursor of inequalities in adulthood.