Health Order
Firstborn, middle child, or youngest? Here’s what your family ranking reveals about your medical destiny.
Birth order theories of personality make great cocktail party fodder. Experts have been arguing for years about whether family position can account for kids’ personality differences.
There’s increasing evidence that your place in the family lineup can have an impact on your physical health. Of course, there’s nothing you can do to change your birth order. But you can make sure to enjoy the benefits that come with it—and steer clear of the risks. Here, a birth order–based cheat sheet to help you and your loved ones beat your odds of allergies, asthma, accidents, and more.
Firstborn
Family reveals destiny
The good news a recent study in Science magazine showed that firstborns score an average of 3 points higher on IQ tests than their younger siblings. And being brainy goes along with better health, found a study from the University of Glasgow that suggests children who scored higher on IQ tests were less likely to develop coronary heart disease and some cancers.

Watch for
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Allergies and Asthma
In a review of over 50 studies, researchers found that oldest kids are more likely to suffer from allergies, hay fever, eczema, and even asthma. The reason might be that firstborns are overprotected: many are exposed to few bacteria or viruses until they start school; while younger siblings battle the bugs older sibs bring home—and therefore may develop stronger immune systems.
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Testicular Cancer
A study from the Karolinska Institute in Stockholm found that firstborn men have a greater risk of testicular cancer. The eldest is typically exposed to higher estrogen levels in the womb than later-born sibs. Which may up his risk of disease?
Keep an eye out this relatively rare cancer can strike men as young as in their teens but is curable if found at an early stage.
Middle Child

The good news Your risk of gum disease is 5% lower, probably because your immune system got an early workout from the germs your older brother or sister brought home and is better able to dispatch oral bacteria.
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Depression
A University of Wisconsin study found that parents spent less money and nearly 10% less time caring for them, compared with older or younger kids. And a University of Pennsylvania study found middle kids reported significantly more depressive symptoms.
Make sure second-born isn’t second-class.
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Chronic Fatigue Syndrome
Preliminary research from the University of Medicine and Dentistry of New Jersey suggests that middle kids are slightly more likely to suffer from CFS than their younger or older siblings.
If you feel exhausted for 6 months or more, and rest doesn’t help, you may have CFS. If your seemingly healthy child refuses to play outdoors or is not excited about going for a picnic, it’s time to seek help.
Minimize your risk Experts say CFS may be triggered by an infection—so good hygiene, staying current with vaccines and healthy eating may offer you protection.
Youngest
The good news your risk of allergies is lower, thanks to those hand-me down germs. Another benefit of being the baby: in Italian research, young adults who grew up with older siblings were 10% less likely to develop Hodgkin’s disease (cancer of the immune system) than single children.
* Accidents and Preventable Diseases
A recent study of childhood accidents at a Jerusalem hospital found that kids with three or more siblings were 50% more likely to be injured than those from smaller families. When parents are spread thin and supervision gets lax, other important protections can fall by the wayside, too: a study of London-born children found their odds of being vaccinated decreased 20% for each additional child in the family.
Be vigilant Vaccinate your kids. And talk with your doctor about whether you should roll up your own sleeve. You may benefit from shots that weren't available when you were younger and may need boosters for others.