Breastfeeding and healthier infant diets linked to lower obesity risk by age nine

Healthier feeding practices in the first year of life may help reduce a child’s risk of obesity by primary school age, according to new research from Iceland – although experts stress that obesity risk is shaped by many factors beyond infancy.

The large national study, published in Maternal & Child Nutrition, found that children whose early diets were less well aligned with infant feeding guidelines were more likely to be living with obesity at ages six and nine.

Researchers analysed data from 12,848 children born in Iceland between 2009 and 2015, using national health and birth registries. Infant feeding information was collected during routine health checks across the first year of life.

The team used a composite “infant diet score” (IDS) to assess how closely each child’s early feeding patterns matched recommended guidelines. The score included duration of breastfeeding, age at introduction of cow’s milk and food and vitamin D supplementation.

Children were grouped into five equal categories (quintiles) based on their IDS, from lowest to highest alignment with guidance. Body mass index (BMI) was then assessed at 2.5, 4, 6 and 9 years of age. By age nine, 23 per cent of children were classified as overweight and 14.6 per cent as obese. At age six, 19.1 per cent were living with overweight and 8 per cent were living with obesity.

Children in the two lowest IDS quintiles – indicating poorer alignment with infant feeding guidelines – were significantly more likely to be living with obesity at ages six and nine than those in the highest quintile. Overall, these children had around 37 to 58 per cent higher odds of living with obesity in later childhood.

The researchers emphasised that the study shows an association, not cause and effect. While early nutrition appears to play a role, childhood obesity is influenced by a wide range of factors, including family circumstances, physical activity, food environments and socioeconomic conditions later in life.

As a registry-based observational study, the findings may also be affected by missing dietary data and unmeasured influences during childhood.

Despite these limitations, the study adds to growing evidence that supporting healthier feeding practices in infancy – including breastfeeding and appropriate introduction of solid foods – could form part of a wider, long-term strategy to reduce childhood obesity risk.