(HealthDay News) – High pollen exposure in utero late in pregnancy is associated with an increased risk of asthma hospitalization during the first year of life, according to a study published online Nov. 7 in Allergy, Asthma & Clinical Immunology.
Adrian J. Lowe, PhD, MPH, from Umeå University in Sweden, and colleagues assessed the effect of pollen exposure in the first and last 12 weeks of pregnancy and the first 12 weeks of infancy for all children conceived by women residing in Stockholm between 1988–1995. Hospital admission data were used to assess respiratory conditions in the first year of life.
The researchers found that, by age 12 months, 940 of 110,381 children had been hospitalized for asthma. There were marked seasonal variations and between-year differences in pollen levels. There was an increased risk of asthma hospitalization for those exposed to high levels of pollen in the last 12 weeks of pregnancy (adjusted odds ratio [aOR], 1.35 for highest quartile vs. remaining infants). Among children of mothers who smoked heavily, exposure to high levels of pollen in the first three months of life was associated with a significantly reduced risk of asthma hospitalization (aOR, 0.76).
“Replication of these findings is needed, as the results are somewhat surprising,” the authors write. “If replicated, these findings may lead to mechanistic studies that help elucidate the pathogenesis of late pregnancy pollen exposure on respiratory outcomes, which could have therapeutic implications.”