Large-scale study finds children with obesity face markedly higher risk of limb fractures

Key Takeaways: 

• Children with obesity at the age of starting school have nearly a five-fold higher risk of bone fractures during childhood compared with children of a healthy weight.
• Analysis of almost 467,000 children in Catalonia showed obesity at age four was associated with a 70% higher risk of lower limb fractures and a 20% higher risk of upper limb fractures.
• Findings highlight the long-term health implications of obesity in the preschool years, reinforcing the need for early intervention and further research.
  

Growing concern over childhood obesity

The rising prevalence of childhood obesity is a major global public health challenge. It has already been linked to a wide range of conditions in later life, including cardiorespiratory disease, type 2 diabetes, and mental health disorders. Much of the research in this field has focused on obesity in older children and its consequences for adult health. Less is known about how excess weight in the preschool years influences immediate health outcomes during childhood and adolescence.

A new study, published in the Journal of Bone & Mineral Research and supported by the NIHR Oxford Biomedical Research Centre, sought to address this gap by examining whether obesity at the age of school entry is associated with an increased risk of fractures in later childhood.

Study aims and design

“The primary aim of the study was to determine if elevated body mass index (BMI) just before starting school at age 4 years was associated with an increased incidence of fracture in childhood,” explained Jennifer Lane, Versus Arthritis Clinical Research Fellow in Orthopaedic Surgery at the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences and lead author of the paper. “We found that elevated body weight at the age of starting school increased the risk of breaking a bone later in childhood.”

To investigate this, the research team – consisting of scientists and doctors from the United Kingdom and Spain – analysed the anonymised health records of 466,997 children living in Catalonia. As part of routine healthcare check-ups before starting school, each child was weighed and measured, and their BMI calculated. The researchers then followed the health of these children until they reached 15 years of age, or until data were no longer available due to other reasons such as moving away.

Key findings

At baseline, 5.7% of the children were classified as overweight and 2.0% as having obesity according to their BMI. The results showed a clear link between higher BMI at preschool age and later fracture risk:

• Children with obesity at age four faced a 70% higher risk of lower limb fractures and a 20% higher risk of upper limb fractures compared with peers of a healthy weight.
• Children with overweight had a 40% higher risk of lower limb fractures and a 10% higher risk of upper limb fractures.
  

These findings underscore that excess body weight at the point of starting school is not only a predictor of long-term health risks but also increases vulnerability to fractures during the remainder of childhood.

Next steps and research implications

Jennifer Lane highlighted the importance of building on this work to understand the underlying biological and mechanical mechanisms: “More research is needed to further understand the mechanisms underlying this correlation. Our study adds to a body of work that supports further research into the role that pre-school obesity has in health problems in childhood and beyond.”

While the precise pathways are not yet fully understood, potential factors may include greater force exerted on bones during falls, differences in bone structure or density, or changes in physical activity patterns among children with overweight or obesity.

Broader significance

The study is one of the largest of its kind to investigate fracture risk in relation to BMI measured at preschool age. Its findings highlight the importance of early monitoring of weight and growth, as well as timely interventions that support healthy development before children enter formal education.

The evidence reinforces that obesity in the early years is not only a future risk factor for adult disease but also has immediate and tangible consequences for musculoskeletal health during childhood.