First-born children have greater difficulty absorbing sugars into the body and have higher daytime blood pressure than children who have older siblings, according to new research.
The study, conducted by the Liggins Institute at the University of Auckland, was published this week in the Journal of Clinical Endocrinology and Metabolism.
Researchers led by Prof Wayne Cutfield documented a 21 percent drop in sensitivity to insulin, the hormone which controls blood sugar levels, and slightly higher blood pressure among first-born children. These phenomena are known risk factors for conditions such as diabetes and cardiovascular disease later in life.
On the plus side, first born children were on average taller and slimmer than their later born counterparts.
The authors theorise that the metabolic differences in younger siblings might be caused by physical changes in the mother’s uterus during her first pregnancy. As a result of the changes, nutrient flow to the fetus tends to increase during subsequent pregnancies.
“Although birth order alone is not a predictor of metabolic or cardiovascular disease, being the first-born child in a family can contribute to a person’s overall risk,” says Prof Cutfield.
“Our results indicate first-born children have these risk factors, but more research is needed to determine how that translates into adult cases of diabetes, hypertension and other conditions.”
The research has attracted attention from international media. Examples include:
Stuff.co.nz: Eldest children health risk
Daily Mail: First-born children are more likely to get diabetes… but they are taller and slimmer too
CBS News: Diabetes risk greater in first-borns, says study: What explains link?
New York Daily News: Firstborn children may have greater risk of heart disease, diabetes: study
Medical News Today: Firstborns Have Higher Risk Of Diabetes, High Blood Pressure
NPR: Born First And Headed For Health Trouble?