October 20, 2010
Allergies Tied To Early Pregnancy
A new study published on Wednesday found that a child's risk of allergies could be linked to the season that coincides with the first three months of pregnancy.
Researchers cast an eye over the health records of 5,920 children born between 2001 and 2006 in the southern Finnish province of South Karelia, 961 of whom were given skin tests for allergies by the age of four.
Ten percent of those who were born in October and November tested positive, twice the proportion of those born in June and July. Allergy sensitivity among the October-November babies was especially strong for milk and egg allergies.
Investigators suggest the reason is that the October-November babies were exposed to high concentrations of birch and alder pollen while they were at a key stage of fetal development.
These trees have a peak pollen period in April and May.
The lowest pollen period was December and January, which explains why children born in June and July had the lowest allergy sensitivity.
The researchers say that exposure in the womb to powerful allergens at a crucial early phase of pregnancy could affect the development of the baby's immune system.
The study was published in the Journal of Epidemiology and Community Health and was headed by Kaisa Pyrhonen of the Institute of Health Sciences at the University of Oulu.
The study follows up previous studies' results carried out in Sweden, Japan and the Netherlands that children born in the northern hemisphere's autumn or winter are more prone to eczema and asthma-like wheeze, and have higher levels of antigens in the blood than children born in spring or summer.
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