First born children more likely to be obese with high blood pressure


If you’re the first born in your family, you’ve no doubt boasted to your siblings about how it’s been proven the eldest is the smartest. Being an overachiever, reliable and dominant are also common traits seen in the eldest children, but new research suggests it’s not all rosy at the top, and being the first born can actually work against you in the health stakes.

A team of researchers, lead by Professor Sandra Black of the University of Texas at Austin, analysed the health records of 400,000 Norwegian people, spanning nearly 25 years.

It was found that the oldest child is more likely to be less healthy in terms of “physical markers such as blood pressure, triglycerides (a form of dietary fat made by the liver), and indicators of overweight and obesity”.

“For example, compared to fifth borns, first borns are about five per cent points more likely to be obese and seven per cent more likely to have high blood pressure. So, unlike education or earnings, there is no clear first-born advantage in health,” Professor Black said.

“However, first borns are about 13 per cent less likely to smoke daily than fifth borns and are more likely to report good physical and mental health. Later borns also score lower on wellbeing with fifth borns being about nine per cent less likely than firstborns to report that they are happy.

“When we explore possible mechanisms, we find that early maternal investment may play a role in birth order effects on health.”

It’s not all bad news though, as the eldest children are more likely to consider themselves happy, and it was found mental health generally decreases with birth order.

Gender wasn’t found to play a role.

Speculating on the results, Professor Black said it could be to do with first borns being lighter at birth meaning “a lower nutrient flow to first borns in utero may affect their regulation of fat and cause them to store more fats in adulthood”.

She adds the tendency for the oldest to be career-orientated and intense may account for the high blood pressure.

Findings have been published in the journal Economics and Human Biology.

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