Maternal late-pregnancy serum unmetabolized folic acid concentrations are not associated with infant allergic disease - A prospective cohort study

Background The increase in childhood allergic disease in recent decades has coincided with increased folic acid intakes during pregnancy. Circulating unmetabolized folic acid (UMFA) has been proposed as a biomarker of excessive folic acid intake. Objective We aimed to determine if late-pregnancy serum UMFA and total folate concentrations were associated with allergic disease risk in the offspring at one year of age in a population at high risk of allergy. Methods The cohort consisted of 561 mother-infant pairs from Western Australia. To be eligible the infant had a first-degree relative (mother, father or sibling) with a history of medically diagnosed allergic disease. Maternal serum was collected between 36 and 40 weeks of gestation. UMFA concentrations were measured by tandem mass spectrometry using stable isotope dilution, folate concentrations were determined using the microbiological method with standardized kits. Infant allergic disease outcomes of medically diagnosed eczema, steroid treated eczema, atopic eczema, IgE-mediated food allergy, allergen sensitization and medically diagnosed wheeze were assessed at 1 year of age. Results Median (IQR) for UMFA and serum folate was 1.6 (0.6-4.7) and 53.2 (32.6-74.5) nmol/L, respectively. Of the infants, 34.6% had medically diagnosed eczema, 26.4% allergen sensitization and 14.9% had an IgE-mediated food allergy. In both adjusted and unadjusted models there was little evidence of association between UMFA or serum folate and any of the infant allergy outcomes. Conclusion In this cohort of children at high risk for allergic disease there was no association between maternal UMFA or serum folate measured in late pregnancy and allergic disease outcomes at 1 year of age.