The findings of a recent Finnish study suggest that children’s chances of developing food allergies may depend on when they are conceived.
Researchers studied 5,973 children from the south-east of Finland between 2001 and 2006. They found that children who were conceived in January or February had an 11% risk of susceptibility to a food allergy. Those conceived in September or October had a 6% chance. In general, a higher incidence of positive food allergy results was found among children conceived in October and November than those born in other months.
Lead researcher Kaisa Pyrhonen said: "The incidence of such results was particularly high and especially pronounced for milk and egg among children who had their 11th gestational week in April or May, the season during which the concentrations of pollen from birch and alder are highest in the area concerned”.
The exposure to tree pollen during the period in which the foetus is developing antibodies could explain these trends. Low levels of vitamin D in the mother following the winter could also contribute to the reduced immune defences in the unborn child.
Lindsey McManus of Allergy UK said that more research was needed, especially into the potential genetic basis of allergies. Allergies are often passed down in families, and the genetic predisposition is very strong. It would be interesting to see whether parents would be influenced by this research as to when they decide to start a family, but I think more evidence would be necessary.