A new study has found that younger siblings are more likely to suffer from cardiovascular health issues than their older brothers and sisters.
Dr Peter Nilsson of Lund University in Sweden and his research team analysed data of more than 2.5 million Swedes who were born between 1932 and 1990 and investigated the health implications of sibling number and birth order for the first time.
The scientists discovered the total number of siblings affected a person's risk of cardiovascular health issues.
"Compared to men with no siblings, those with 1-2 siblings had a lower risk of cardiovascular events. Those with 4 or more siblings had a higher risk," lead author Dr Nilsson told The Telegraph. "Women with 3 siblings or more had an increased risk of cardiovascular events, compared to women with no siblings."
Furthermore, the findings showed that the first-born child, if it is male, is eight per cent more at risk of suffering from coronary heart disease later in life than their younger sibling, and if the family continues to expand, the youngest of the three children is 13 per cent more at risk of the condition compared to the eldest.
If the first-born child is female, they are seven per cent less likely than their younger sibling to develop cardiovascular issues.
Additionally, the researchers discovered that a girl with two older siblings is two per cent more at risk of cardiovascular disease and 14 per cent more at risk of heart disease than the eldest, while a boy with four older siblings has a seven and 23 per cent increased risk, respectively.
However, the study, published in the BMJ, was observational so the scientists are unable to establish a causal link between the two.
Explaining possible reasons for the findings, lead author Dr Nilsson told the publication, "First-borns receive more parental attention, expectations and stimulation. But language development might be faster in later born siblings as they will have older brothers/sisters to learn from.
"To be a first-born means that you are expected to behave more correctly and avoid bad things (alcohol overuse, drugs, tobacco) that later born siblings with less parental supervision may be prone to try."