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Asthma risk determined at birth

The chances of a child developing asthma or other allergies may largely be fixed by the time they are born, a study suggests.

Researchers at the David Hide Asthma and Allergy Centre in Isle of Wight, found that babies with high levels of antibodies in their umbilical cord blood were more at risk. Antibodies are a sign that the baby's immune system has begun to respond to the irritants that cause allergies.

The researchers analysed data on cord blood serum samples taken from more than 1,300 children born between 1989 and 1990. Each child was then assessed at ages one, two, four and ten to find out if they ahd developed any allergies.

The cord blood sample was measured for levels of a chemical called IgE, which is produced by the immune system in response to the presence of allergens. Children who had high umbilical cord blood levels of IgE at birth were around twice as likely to have become sensitised.

One in 10 of the children had been diagnosed with asthma by the time they were one to two years old, and by the age of four, one in seven (15.2%) of the children had asthma. Almost 13% of the children had asthma by the time they were 10.

High IgE cord blood levels were not associated with the development of asthma up to the age of four. But children with high IgE levels in their umbilical cord blood were around 66% more likely to have a diagnosis of asthma by the age of 10.

The researchers say dramatic changes in the immune system occur during pregnancy and the immune response of the foetus - to make IgE antibodies - can start as early as the 11th week. It is thought that this can be influenced by the mother's environment as the same factors affecting her will affect the unborn baby.

Lead researcher Dr Hasan Arshad told BBC News Online, "Over the last 10-15 years a lot of research has focussed on the early life influences that may contribute to the development of asthma in a child, but it may be that we have to go back even further and look at the pregnant woman's environment."

However, Dr Seif Shaheen, of King's College London and Asthma UK Research Fellow, said it would be wrong to overlook the impact of exposure to allergens following birth.

"Whilst there is an increasing body of evidence that the environment in the womb may influence the development of atopy (allergy) and asthma, it is also likely that the environment once the child is born plays an important role too.

"We are all born, to a lesser or greater extent, with our immune system skewed towards an allergic type response.

"Environmental exposures after birth are likely to determine whether this allergic tendency carries on through childhood or disappears.

Allergic conditions in the UK have increased by four times in the last 20 years.

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