A new study suggests that babies born by cesarean section are five times more likely than babies delivered vaginally to develop allergies by the time they turn two.
The findings follow earlier research that demonstrated babies born by c-section are more likely to develop asthma than those delivered naturally.
When exposed to high levels of common allergens in the home (from cats, dogs, and dust mites), the chance of developing allergies for c-section babies is five times greater than for those born naturally, the new study found.
The study's lead author, Christine Cole Johnson, Ph.D., MPH, said the findings further advance the hygiene hypothesis that early childhood exposure to microorganisms affects the immune system's development and onset of allergies.
"We believe a baby's exposure to bacteria in the birth canal is a major influencer on their immune system," said Cole Johnson, the chair of Henry Ford Department of Health Sciences.