The infants of mothers who used folate supplements during their first trimester appear to have a slightly higher incidence of wheeze and lower respiratory tract infections up to 18 months of age, according to findings of a study conducted in Norway.

Because these findings are preliminary, “women should not panic and they should definitely continue with their folic acid supplements,” lead author Dr. Siri E. Haberg stressed in an interview with Reuters Health.

Women are advised to increase their folic acid intake during their childbearing years to reduce the risk of congenital malformations in their offspring, Dr. Haberg and co-authors note in the Archives of Disease in Childhood. However, studies in mice indicate that folic acid increases gene activity during pregnancy and causes allergic asthma genetic patterns in offspring.

Haberg, at the Norwegian Institute of Public Health in Oslo, and her associates analyzed data from the Norwegian Mother and Child Cohort. The current analysis included 32,077 children born between 2000 and 2005.

According to questionnaire responses, 22.3 percent of mothers used folate supplements in the first trimester only and 42.6 percent used supplements throughout pregnancy.

After adjusting for folate exposure later in pregnancy and in infancy, the relative risk for wheeze was increased by only 6 percent for children up to 18 months of age who were exposed in the first trimester. Corresponding relative risks for lower respiratory tract infections and for hospitalizations for lower respiratory tract infections were 9 percent and 24 percent, respectively.

As Haberg pointed out, “documentation of the preventive role of folic acid supplements in congenital malformations is well established, while our data (regarding respiratory illness in early childhood) are only the first such findings in humans, and we don’t even know if the association is causal.”

SOURCE: Archives of Disease in Childhood, online December 2, 2008.