Pollen exposure during pregnancy affects child's risk of early asthma

A woman’s exposure to high pollen levels late in pregnancy increases her risk of having a child with early asthma, according to a new study. 

The researchers at the Division of Occupational and Environmental Medicine at Umeå University in Sweden followed 110,000 pregnancies in the Stockholm area.

They found that high levels of pollen exposure during the last 12 weeks of pregnancy resulted in a significantly increased risk of hospitalization for asthma symptoms in the first year of life for a child. The analysis was adjusted for factors such as maternal smoking and pollen season.

They say there may be several reasons for the association. High pollen exposure of pregnant women with pollen allergies may trigger reactions and asthma symptoms that then affect the unborn child's immune system development. It is also possible that pregnant women with severe reactions to pollen suffer complications and sometimes give birth earlier than they otherwise would have done, which in itself increases the risk of respiratory problems in the child.