New research from Umea University has shown that when a pregnant woman is exposed to elevated pollen levels in late pregnant there is a greater risk of a baby developing asthma. So children who are born in the early summer just after the highest pollen counts of late Spring, may be more likely to develop asthma.
In general children born during pollen season (April – June in the northern hemisphere) are more likely to develop allergies in general.
“The investigators found that children born to mothers who were exposed to high pollen levels during the last 12 weeks of pregnancy had a significantly increased risk of hospitalization for asthma symptoms in the first year of life.” Robert Preidt, reporting for Nih.gov
This piece of research really has shed new light on the causes of asthma. The main conclusion of the study by Adrian Lowe and his colleagues was that “high levels of pollen exposure during late pregnancy were somewhat unexpectedly associated with an elevated risk of hospitalisation for asthma within the first year of life.” You can read the full research paper by following the link below.
Why is this happening though? It may simply be that children in countries which have very intensive agriculture may be exposed to far greater pollen concentrations than humans evolved to deal with. While grass pollens and tree pollens trigger hay fever events, agricultural pollens are generated in massive quantities and are released over a shorter time-frame as the life cycle of the crops are controlled by the farmers, not by nature.
It may be the modern farming is literally poisoning children while they are still developing in the womb.
The research also reported that children born during the pollen season are at lower risk than those born just afterwards. Early Spring babies seems to be more tolerant than late Spring and Summer babies. However, this trend was only seen in children of mothers who were heavy smokers. So there is another relationship at play which still needs to be investigated.
Incidentally, the UK has recently seen a fall in new asthma cases, and the ban on smoking in public places is thought to be a major factor in the fall (Brimelow, 2012). Although wetter seasons may also contribute.
Winter Babies May Be Healthier!
So, babies born in winter may be healthier. Maybe the ideal time to conceive is during mid-summer period so that the baby is then born in late winter e.g. conceived June to be born in March before the worse of the pollen, or maybe conceived in May to be born in February.
Whatever the reason for the fall in the UK, it is good news. But apart from encouraging mothers to time the birth of their children to fall in the late Autumn, Winter or Early Spring months, what else can there be done to reduce risk?
If you want to increase your chances of getting pregnant at the “right time” of the year, then learn when in the month you are most and least fertile.
Pollen exposure in pregnancy and Infancy and risk of asthma hospitalisation – a registry based cohort study (pdf). Lowe AJ, Olsson D, Bråbäck L, Forsberg B: Allergy, Asthma & Clinical Immunology. 2012 Nov 7; 8 (1): 17. doi: 10.1186/1710-1492-8-17
Pollen exposure during pregnancy affects child’s risk of early asthma – Press Release from Umeå University
Mother-to-Be’s Pollen Exposure May Boost Asthma Risk in Baby By Robert Preidt. Thursday, January 10, 2013. Source: Umea University, news release, Jan. 7, 2013
Childhood asthma ‘admissions down’ after smoking ban, By Adam Brimelow, Health Correspondent, BBC News. 21 January 2013.