Children’s health could be improved by having a younger sibling

Becoming an older brother or sister by the time a child begins school could lower their risk of becoming obese, according to a recent study led by the University of Michigan.

The birth of a sibling, especially when the child was between about 2 and 4 years old, was associated with a healthier body mass index (BMI), according to the research. Children the same age who didn't have a sibling were nearly three times more likely to be obese by their first year of school.

"Research suggests that having younger siblings – compared with having older or no siblings – is associated with a lower risk of being overweight. However, we have very little information about how the birth of a sibling may shape obesity risk during childhood," says senior author Julie Lumeng, a developmental and behavioural paediatrician at the University of Michigan's Mott Children's Hospital.

The authors have speculated that it could be down to parents changing the way they feed their child once a new sibling is born. With children developing long-lasting eating habits at around three years old, changing dietary habits may have a significant impact.