Babies born with a low birth weight may be less active in later life

Individuals who are born with a low birth weight are less likely to be good at sports at school or participate in exercise later on in life.

The study, published in the journal Medicine & Science in Sports & Exercise, used data from the Medical Research Council (MRC) National Survey for Health and Development, a unique birth cohort that closely monitors a group of people all born in the same week in March 1946. This particular research involved data from 2,739 of study participants.

Although previous studies have shown that a low birth weight can affect sporting ability and exercise levels at a younger age, this is the first study to show that it also relates to exercise across adulthood and into later life.

The researchers at the MRC Unit for Lifelong Health and Ageing at University College London (UCL) classed study members with a low birth weight as those who weighed up to 5.5 pounds, or 2.5 kilograms, at birth. The researchers then analysed data collected over several decades to find that those with a low birth weight were more likely to be rated as below-average at school sports by their teacher at age 13. They also found that those with a low birth weight were less likely to take part in exercise and sports across adulthood, from ages 36 to 68.

Given that babies born with a low birth weight now have an increased chance of survival into adulthood compared to babies born in 1946, the findings will have even greater public health implications for current and future generations.

Dr Ahmed Elhakeem, a PhD researcher at the MRC Unit for Lifelong Health and Ageing at UCL, and lead author of the study, added: "We know that regular exercise provides many health benefits including a longer life so it's important that parents, teachers and doctors recognise that those born with a low birth weight might require more support than others in order to achieve sustained physical activity throughout their lives."

Professor Rebecca Hardy, a programme leader at the MRC Unit for Lifelong Health and Ageing at UCL and co-author of the study, said: "The finding that low birth weight was related to less exercise in later life was not explained by socioeconomic circumstances and school sporting ability, both of which are known to be associated with exercise in adulthood. This means that other developmental and social processes are also likely to be involved."

The next stage for this research will be to better understand the developmental and social mechanisms behind these findings which could lead to effective interventions for those born small to support participation in sport at an early age and encourage exercise in later life.