High folate levels during pregnancy linked to increased asthma risk in children.

Using data from the Norwegian Mother and Child Cohort Study, Stephanie London (National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA) and co-researchers retrospectively assessed plasma folate levels in the second trimester of pregnancy in 507 mothers of children who had developed asthma by the age of 3 years, and in 1,455 mothers of children who had not developed the disease by this age. Analysis revealed that children born to mothers in the highest quintile of plasma folate levels were 1.66 times more likely to have asthma than those born to mothers in the lowest quintile. Compared with a reference category of folate levels below the 70th percentile in mothers who did not use folate supplements, children born to mothers with folate levels between the 70th and 95th percentiles were 1.34 times more likely to have asthma, while children born to mothers with folate levels above the 95th percentile were 1.44 times more likely to have the disease. Conclusion: Higher maternal plasma folate levels in pregnancy were associated with asthma at age 3. The next step is to follow-up these children to an age when asthma can be more reliably diagnosed.