Firstborn insulin 'less effective'
Firstborns are more likely to produce less effective insulin than people who have older siblings, research has shown.
Insulin issues are a known risk factor for diabetes and higher blood pressure, but the researchers said further studies are needed to determine how this translates into adult risk factors.
This is because of the influence puberty and lifestyle can have on health as well.
Results from the study, which was completed by the University of Auckland in New Zealand, revealed that there was a 21% drop in insulin sensitivity among firstborn children. They also had higher blood pressure.
Wayne Cutfield, from the university, explained that although the evidence for birth order does not predict metabolic or cardiovascular disease, it can affect a person's overall risk.
The research, which was conducted via the Liggins Institute, included 85 healthy participants aged four to 11, which included 32 firstborns.
The data collected included details of fasting lipid and hormone profiles, as well as body composition, height and weight.
A 24-hour ambulatory device was also used to monitor their blood pressure, while regular blood tests were taken to monitor glucose.
It is thought that the changes in insulin sensitivity could be the result of changes in the uterus during a first pregnancy that increase the flow of nutrients to fetuses.
The findings have been published in the Journal of Clinical Endocrinology & Metabolism .
Copyright Press Association 2013
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