Caesarian birth greatly increases a baby’s chances of developing allergies, a study has found.
Infants delivered by C-section are five times more likely than those born naturally to become allergic to common triggers such as dust mites and pets, according to the research.
Scientists believe babies are left vulnerable by avoiding the journey through the birth canal, which would normally expose them to their mother’s bacteria.
The discovery lends support to the “hygiene hypothesis” that links childhood allergy to over-clean conditions early in life.
Lead researcher Dr Christine Cole Johnson, from the Henry Ford Hospital in Detroit, US, said: “This further advances the hygiene hypothesis that early childhood exposure to micro-organisms affects the immune system’s development and onset of allergies.”
Dr Johnson’s team studied 1,258 newborn babies and assessed them when they were one month, six months, one year and two years old. By two years old, babies born by C-section were much more likely to have developed allergies to triggers in the home, such as the droppings of house dust mites and dead skin shed by dogs and cats.
Umbilical cord and stool samples from each baby were analysed, together with blood samples from both parents, breast milk and household dust.
Information was also collected on every family’s history of allergy or asthma, household pets, tobacco smoke exposure, baby illnesses and medication use.
The research was presented yesterday at the American Academy of Allergy, Asthma and Immunology in San Antonio, Texas.