First-born children are more likely to suffer from food allergies than their younger siblings, Japanese researchers have found.
Researchers from Japan's Shiga Medical Center for Children examined data on 13,000 children, between the ages of 7 and 15. They found 4 per cent of first-born children had food allergies, compared with 3.5 per cent of second-born children, and 2.6 per cent of children born later.
According to the health site My Health News Daily, researchers aren't certain why the prevalence of food allergies changes in relation to birth order, but one theory is that multiple pregnancies could alter a mother's immune system, which could affect a child's development in the womb.
Another possible explanation could be related to the hygiene hypothesis, which suggests a super-clean environment may cause one's immune system to overreact, causing allergic reactions. As My Health News Daily reports, more children in a household means more germs.
Increased exposure to microbes is believed to be the reason why children who grow up on farms tend to be less likely to develop asthma, according to a German study released last month.
That study found children who lived on farms were up to 50 per cent less likely to develop asthma than children living in non-farm environments.
Are we too cautious about keeping our children clean?
For all you first-borns out there, do you have more allergies than your younger brothers and sisters?