London, Aug 31 : Researchers in New Zealand have found that living on a farm during pregnancy may help reduce the chance of the child developing asthma, eczema and even hayfever.
They suggest that exposure to animals and the bacteria they carry may affect the foetus's immune system.
The findings are based on a new study, conducted at Massey University, which has suggested that living on a farm, with regular contact with animals, during the early years of life, could cut the risk of asthma and other allergic diseases.
The study of more than 1,300 farmers' children goes further, suggests that this protection could start building even before birth.
It showed that the greatest apparent protection - a 50 percent reduction in asthma, and an even greater reduction in eczema and hay fever - was gained by children whose mothers had been exposed to farm life during pregnancy, and who currently lived on a farm.
Although, the reasons why this might happen are unclear, they are likely to be related to the way that the child begins to develop its immune system.
Living on a farm means frequent contact with animal bacteria, perhaps through the consumption of unpasteurised milk, or contact with the animals directly.
According to the researchers, this might suppress the production of particular immune cells linked to the development of asthma.
However, they suggested that while exposure during pregnancy might be useful, it might only persist if the child was exposed after its birth as well.
The findings are unlikely to lead to any change in current advice to pregnant women, which urges caution about contact with certain farm animals.
In particular, an infection, which can cause miscarriage in pregnant ewes, can lead to the same result in humans.
The faeces of other animals can also carry infections, which can affect a pregnancy.
This study adds to existing evidence supporting the hygiene hypothesis, which states that early exposure to potential allergens results in a reduced risk of asthma development," BBC quoted Dr Elaine Vickers, research manager at Asthma UK, as saying.
"However, the causes of asthma are still largely unknown and the processes involved in asthma development are incredibly complicated, including family history, environment and lifestyle," Vickers added.
The study is published in the European Respiratory Journal.