Research has shown that if you’re the most senior of your siblings, you’ll likely have a higher IQ. However, the latest study shows you may also be more at risk of obesity and high blood pressure.
A 25-year study of almost 400,000 Norwegians shows that, while the eldest child in a family is more likely to be be taller (by one eighth of an inch) they are also four per cent more likely to be overweight and two per cent cent more likely to be obese.
Lead author Professor Sandra Black of the University of Texas at Austin told Mail Online:
‘Overall, we find that first-borns are less healthy in terms of physical markers such as blood pressure, triglycerides, and indicators of overweight and obesity.
‘For example, compared to fifth-borns, first-borns are about 5 per cent points more likely to be obese and 7 per cent more likely to have high blood pressure. So, unlike education or earnings, there is no clear first-born advantage in health.
‘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 well-being with fifth-borns being about 9 per cent less likely than first-borns 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.’
The good news? First born children are more likely to describe themselves as happy adults. The percentage of adults who describe their mental health as being very good tends to decline with birth order.
The study was published in the journal Economics and Human Biology.