Children with affluent parents may have weaker bones than those from poorer families, new research suggests.
Educated mothers have taller, thinner children, the study says
Bristol University scientists examined nearly 7,000 youngsters as part of their Children of the 90s project.
By age nine, children with graduate mothers were taller, but had longer bones that could be more prone to fractures, they found.
The researchers do not know exactly why this is but believe it is mainly due to environmental factors, such as diet.
The children from privileged backgrounds were an average 1.5cm taller and 1kg lighter than those whose mothers had no qualifications.
However, their longer, slender bones may be weaker and prone to osteoporosis and fractures in later life, the study authors believe.
By doing scans the researchers discovered the bones of the children from more privileged backgrounds contained the same amount of calcium as the bones of the children from less affluent families, even though they were much longer.
Senior investigator Dr Jon Tobias said: "If you think of the bones as scaffolding, the strength is related to the diameter. If you have a structure that is wider it tends to be much stronger.
"Being less affluent is normally associated with adverse health effects, so our findings are quite unusual."
He said it was possible that the children from more affluent backgrounds might have a better diet throughout their life that would, in turn, protect them against bone loss and fractures.
Also, people from less affluent backgrounds might be more likely to have accidents, fall over and break bones, he said.
They plan to follow the children for as long as they can. They already have data on the same children aged 13 that is yet to be published.
Colleague Dr Emma Clark said: "Many people develop skeletal problems later in life. If we can identify contributory factors to this early on, then we should be better equipped to help avoid and manage such problems."
She said most conditions and diseases had some form of social pattern.
"The fascinating fact is that bone mass shows no signs of this, while height and weight do," she said.
"This opens the door to a new focus for researchers and sets us a challenge to find out why, and what the implications of this may be."
It was important to emphasise the role of a healthy diet and regular exercise in maintaining general good health, she added.
A spokesman from the National Osteoporosis Society said: "It's a very interesting study.
"We know that people who are naturally taller do have thinner bones. But this is starting to put socio-economic factors into play which are very important in understanding who is going to be at risk of osteoporosis in future years.
"People rich and poor really need to take a cradle to grave attitude towards osteoporosis and healthy bones."