NEW YORK (Reuters Health) - Babies born to women working with farm animals appear to have significantly less eczema than babies who were not exposed to animals before birth.
A European research team reports in the Journal of Allergy and Clinical Immunology that a mother’s contact with farm animals and cats during pregnancy has a strong protective effect against atopic dermatitis, a serious skin condition also known as eczema, in the baby’s first two years of life.
In eczema, an overactive immune system leads to chronic itchy scaly skin rashes that come and go. Nearly a third of children who develop it before age two go on to develop hay fever or asthma.
The new findings seem to support the idea, known as “the hygiene hypothesis,” that early exposure to diverse microbes trains and tunes a baby’s immune system, making it less prone to allergic overreactions to benign substances later.
Researchers don’t know why some children develop eczema and others don’t, although an interplay between genetics, the environment and the immune system is suspected.
Because mothers can pass on some short-term immunity to their babies, Dr. Caroline Roduit of the University of Zurich and colleagues in Switzerland and Germany wanted to know if moms whose immune systems were regularly challenged by microbes might have children with a lowered risk of eczema.
Previous research has already shown that children of farm families have reduced risk of asthma and allergies, with credit given to the rich microbial life - both pathogens and harmless bugs - that animals contribute to the kids’ environments.
Roduit’s team analyzed mothers’ environmental exposures during pregnancy and the development of atopic dermatitis in their children up to age 2. The study included 1,063 children born to 508 farm families and 555 non-farm families in 5 European countries.
Women answered questions about their exposure to animals, smoking habits and history of allergies. Mothers’ blood was tested and samples of the babies’ cord blood were taken at birth and analyzed.
In all, 17.8 percent of the study children developed a doctor-diagnosed case of eczema by age 2, but differences between the two groups were apparent: just 14.4 percent of the farm children got the condition whereas 20 percent of non-farm children did.
The researchers found that while the all the children of farm moms had lower risk of eczema, the greater the variety of animals (horses, pigs, cows, sheep, rabbits, poultry) their mom contacted, the lower the kids’ risk.
“For each additional farm animal species the mother had contact with, we observed a (risk) reduction of 20 percent,” they wrote. They also found a similar significant association between mothers’ contact with cats and the skin rash disorder in the children.
At birth, the children who would prove least likely to develop eczema by age two had the highest amounts of several immune system-related proteins in their cord blood, the authors note. The proteins are involved in the body’s ability to recognize pathogens.
Although the findings support previous research suggesting that microbe-rich environments such as farms have a protective effect against allergies, the results do not mean pregnant women should seek out new exposures to cats or farm animals.
“We did not study the infectious diseases among our study population,” Dr. Roduit told Reuters Health in an e-mail. “So it is difficult with our results about allergies to change these recommendations about infections that could be dangerous for pregnant women,” she said.
For instance, cats, especially those that go outdoors, can transmit toxoplasmosis, an infection that can lead to premature birth, low birth weight, jaundice, mental retardation, and convulsions when a woman is exposed early in pregnancy.
An estimated 15 percent of women are immune to toxoplasmosis. Women who have been around cats before getting pregnant are more likely to be immune and according to the American Pregnancy Association, their babies are safe.
“Don’t give away your pet, but we cannot recommend actively to take a (new) cat during pregnancy,” Roduit said.
The women in this study worked on small family farms. Roduit said it’s difficult to apply the findings to women working in large industrialized farm settings.
SOURCE: link.reuters.com/xyz59q Journal of Allergy and Clinical Immunology, online November 26, 2010.