It’s always been known that the eldest has a head start in life, the middle child feels left out, and the youngest is rebellious and impulsive.
New research discovered that older siblings don’t always come out on top most notably when it comes to our health.
The ‘babies’ of the family are more likely to be slimmer, healthier and live longer than their elder brothers or sisters, according to a wealth of scientific studies.
Older siblings face upward fight, being prone to obesity, high blood pressure, diabetes, and cancer.
Here is why your place in the family could be the secret to your optimum health.
“Slim and Healthy”
Obesity—which affects more than a quarter of adults— has now overtaken smoking as the leading cause of four types of cancer.
Birth order, overeating, and a lack of exercise could play a role, too.
A 2015 study in New Zealand tracked 13,400 pairs of sisters and discovered those born first were nearly a third more likely to be overweight and 40% more likely to be obese than their younger siblings.
On average, older siblings were 1 lb 4oz bigger.
“The reason is a mystery,” scientists admit.
But Professor Sandra Black, a public health researcher at Columbia University believes the difference may be because, in the first pregnancy a mother’s blood vessels are narrower, reducing the supply of nutrients to a baby in the womb, making them store more fat.
In later pregnancies, blood vessels are more flexible so are inclined to stretch – increasing the flow of blood and nutrients to the baby.
“Lower nutrient flow to first-borns in the womb may affect their body’s regulation of fat, causing them to store more fats in adulthood,” says Prof. Black.
“Younger siblings less likely to get diabetes”
According to the World Health Organization (WHO) diabetes –a condition where the body becomes unable to regulate blood sugar— is the seventh leading cause of death in 2016.
First-borns are more prone to diabetes, according to a study in New Zealand which discovered that older children’s bodies are less responsive to insulin, the hormone that helps muscle cells burn up sugar in the blood, keeping it stable.
Scientists think the poorer health of first-borns maybe because they get a smaller amount of nutrients.
Excess blood sugar is one of the hallmarks of type 2 diabetes – left untreated— can increase the risk of heart attacks, stroke, blindness and amputations later in life.
“Competing increases the blood pressure”
Having a younger sibling is seriously bad for your blood pressure.
Studies involving almost 400 young adults found that those with younger siblings had blood pressure readings up to six% higher than those with older siblings.
Scientists from the University of Massachusetts studied readings in 374 young adults and found little brothers increase readings by up to six% and little sisters by almost 4%.
The reason why is fairly predictable – the arrival of a new sibling means having to compete for parental attention, adding to the stress.
Feeling stressed leads to a surge in the hormone cortisol, which is shown to dramatically increase blood pressure levels.
Older sisters were found to have especially high blood pressure. Scientists think this is because they take on more responsibility around the house, compared to boys, when a new brother or sister arrives.
Another 2017 study – the largest of its type – discovered that older siblings are 7% more likely to suffer high blood pressure at the age of 40.
However, Prof Black says sociological factors may be at play.
“This may be related to the higher stress associated with certain occupations such as managerial positions, which we know first-borns are more likely to do,”
Moreover, findings published in Economics And Human Biology also showed that the effects on blood pressure tend to wear off as family members get older.
“Younger siblings protected from allergies”
The ‘hygiene hypothesis’, where nervous first-time parents over-sterilize, could explain why younger siblings are much less at risk of allergies.
First-borns are almost twice more likely to suffer allergic conjunctivitis, hay fever, and food allergies than third children, and a third more likely than middle children.
Some suggest older siblings pick up infections in school and bring them home, exposing younger siblings to germs at an earlier stage than they were.
Prof. Montgomery says: ‘This boosts younger children’s immune systems, making them less likely to develop allergy-type conditions.’
However, a 2008 study found that the difference in risk begins in the womb.
Scientists studied the placenta blood of 1,200 newborns, all of the varying birth order.
The blood of first-borns was found to contain significantly increased amounts of a genetic marker associated with allergies and asthma.
When researchers followed them up at ages four and ten and performed an allergy test, those with the genetic marker tested positive for allergies. This may partially explain the increasing prevalence of allergies in the Western world, as birth rates have declined.
“Risk of cancer can vary”
Being the eldest can heighten your risk of various cancers, studies suggest.
Boys born as the family’s fourth or fifth child are 70% less likely to develop a testicular tumor than the oldest boy.
Researchers who studied 200 testicular cancer cases and their siblings said a man’s risk of developing the disease may be determined while still in the womb when first-born boys experience greater exposure to the hormone estrogen than younger brothers.
Oestrogen is thought to drive the reproduction of testicular cancer cells.
Brain cancer could also be linked to birth order, according to a German study, which found that having three or more younger siblings trebled the risk of a tumor due to infections passed from younger siblings to older ones, perhaps during late childhood.
Infections passed from older siblings do not seem to carry the same threat.