Cord blood analysis to predict asthma risk in babies

Babies born during the grass pollen season may be at greater risk of developing respiratory diseases such as asthma, according to a new study published in the Environment International.

Bircan Erbas, professor, La Trobe's School of Psychology and Public Health, and colleagues conducted the study to determine the effect of exposure to high grass pollens during pregnancy and soon after birth.

Findings were based on the analysis of cord blood collected from hundreds of babies born in Melbourne, Denmark, and Germany.

They discovered those born during the peak grass pollen season in both hemispheres had high immunoglobulin E (IgE) levels in umbilical cord blood - a marker used to predict the development of allergic diseases.

"We know that outdoor pollen exposure during the first couple of months after birth can lead to allergic respiratory diseases and we suspected that exposure during the later stages of pregnancy may also be important," said Erbas.

"Many studies have shown that babies with high levels of IgE in cord blood can go on to develop allergies later in childhood, but little is known about how these levels are affected by exposure to pollen in utero."

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Key Findings:

• Birth during the grass pollen season had higher pooled odds of cord blood IgE >0.5 kU/L 1.37 (95% CI 1.06, 1.77) in a meta-analysis with little heterogeneity between the three cohorts.


• Cumulative exposure to outdoor grass pollen counts during the entire pregnancy was associated with slightly lower pooled odds but significant.


• High IgE levels were found among babies born in October and December in Melbourne.


• IgE levels were highest for German and Danish babies born around April - the peak pollen season in Europe.


• Being pregnant for an entire grass pollen season may have a protective effect on babies.

"We found these babies had lower IgE levels. This was a significant finding and indicates the possible development of a sensitization barrier. However, more research needs to be done and currently we are working on studies to identify the specific risk time periods of pollen exposure during pregnancy on asthma and allergies in children," Associate Professor Erbas said.

She stressed that the study did not suggest that all babies born during high pollen seasons would develop a respiratory disease or other allergies.

"The study provides new insight that could help us predict and manage diseases like asthma - which are a significant public health burden.

"However, it's important to remember there are a number of factors that can determine who gets asthma or allergies. This is one piece of the puzzle."

"Birth during grass pollen seasons were associated with increased risk of high cord blood IgE in cities from both hemispheres, but high pollen loads in the environment during the entire pregnancy appeared protective. As IgE responses develop during the first months of life, our study findings provide new insights into the mechanisms of grass pollen exposure at birth and shortly after on possible allergic respiratory diseases," concluded the authors.

For further reference log on to http://dx.doi.org/10.1016/j.envint.2018.06.036