London - If you can’t lose weight, blame your siblings.
A study has found that eldest sons tend to be heavier in middle age than those born second.
They also find it harder to process sugar and may be at higher risk of a host of ills from diabetes to cancer and heart attacks.
But, before firstborns add anxiety to their list of woes, the researchers have acknowledged that their study wasn’t watertight.
They made the finding by putting 26 firstborn sons and 24 second-borns through a battery of health tests and comparing the results.
The men, from New Zealand, were all in their 40s and 50s and already overweight.
However, the eldest sons were more than a stone heavier on average.
This meant they were close to being classed as obese.
None of the men had diabetes but the eldest sons found it harder to process sugar in food and turn it into energy.
This put them at risk of going to develop diabetes, as well as heart attacks, strokes and cancer, according to the journal Scientific Reports.
Previous research has shown that eldest children tend to be lighter when they are born but then grow more rapidly in infancy.
They also have higher levels of cholesterol and other dangerous blood fats in their late teens.
The latest research suggests the problems persist in the years to come.
It is not clear why birth order affects health but one possibility relates back to life in the womb.
During a woman’s first pregnancy, arteries that feed the placenta, the lifeline that provides the baby with nourishment, are still maturing.
This could affect the child’s growth at the time – and lead to it being “programmed” to make up for its poorer start by putting on weight later in life.
Subsequent pregnancies are not affected because the key arteries remain in their mature state.
Study author Wayne Cutfield, of the University of Auckland said discovering that eldest children are at greater risk of health problems in their 40s and 50s is important because middle age is a good time to start treating people at risk of health problems later in life.
Plus, the falling birth rate has increased the proportion of only children or firstborns and this could have consequences for the health of the population as a whole.
The professor said: “Any adverse health outcomes associated with being firstborn would affect an increasing proportion of the world’s population.”
However, he cautioned that he studied a small number of men, all of whom lived in the same area and were already overweight.
This might affect how much his findings apply to the general population, including women.
Finally, he compared men from different families, rather than pairs of brothers. - Daily Mail