First-born children have a lower risk of cardiovascular events, but having lots of siblings is associated with an increased risk.
First-born children have a lower risk of events such as heart attacks and strokes than brothers and sisters born later, but people who are part of a large family have an increased risk of these events, according to a study in Sweden, published in BMJ Open.
It is well-known that family history has an impact on a person’s health, including their risk of cardiovascular events, but now there is growing interest in what influence the make-up of a person’s immediate family might have.
Data on fatal and non-fatal cardiovascular and coronary events over the next 25 years were retrieved from national registers in Sweeden.
Analysis of the data showed that first-borns had a lower risk of non-fatal cardiovascular and coronary events than siblings born later.
First-born men had a higher risk of death than second and third-born siblings, while first-born women had a higher risk of death than second-born siblings, but equal to further siblings.
When family size was looked at, compared with men with no siblings, men with one or two siblings had a lower risk of cardiovascular events, while those with four or more siblings had a higher risk.
Compared with those with no siblings, women with three or more siblings had an increased risk of cardiovascular events, while those with two or more siblings had an increased risk of coronary events.
Women with one or more siblings had a lower risk of death.
The authors point out that, as policies to support families and the number of children currently vary widely between countries, their findings could have implications for public health.
The researchers say: “More research is needed to understand the links between sibling number and rank with health outcomes.
“Future research should be directed to find biological or social mechanisms linking the status of being first born to lower risk of cardiovascular disease, as indicated by our observational findings.”