Folate levels in pregnancy and offspring food allergy and eczema

Background: High folate status in pregnancy has been implicated in the increased prevalence of allergic disease, but there are no published data relating directly measured folate status in pregnancy to challenge‐proven food allergy among offspring. The study aim was to examine the association between red blood cell (RBC) folate status in trimester three of pregnancy and allergic disease among offspring. Methods: Red blood cell folate levels were measured at 28‐32 weeks’ gestation in a prospective birth cohort (n = 1074). Food allergy outcomes were assessed in 1‐year‐old infants by skin prick testing and subsequent food challenge. Eczema was assessed by questionnaire and clinical review. High trimester three RBC folate was defined as greater than (>) 1360 nmol/L. Binomial regression was used to examine associations between trimester three RBC folate and allergic outcomes, adjusting for potential confounders. Results: Red blood cell folate levels were measured in 88% (894/1064) of pregnant women. The mean concentration was 1695.6 nmol/L (standard deviation 415.4) with 82% (731/894) >1360 nmol/L. There was no evidence of either linear or non‐linear relationships between trimester three RBC folate and allergic outcomes, nor evidence of associations between high RBC folate and food allergy (adjusted risk ratio (aRR) 2.89, 95% CI 0.90‐9.35), food sensitization (aRR 1.72, 95% CI 0.85‐3.49), or eczema (aRR 0.97, 95% CI 0.67‐1.38). Conclusion: The majority of pregnant women in this study had high RBC folate levels. There was no evidence of associations between trimester three RBC folate and food allergy, food sensitization, or eczema among the offspring, although larger studies are required.