Folate during pregnancy may increase risk of wheeze

Babies of women who take folate supplements during the first trimester of pregnancy may be at increased risk of wheeze and lower respiratory tract infections up to 18 months of age, according to a study published online Dec. 3 in the Archives of Disease in Childhood.

Siri E. Haberg, of the Norwegian Institute of Public Health in Oslo, Norway, and colleagues analyzed data on 32,077 children that was compiled during pregnancy and after birth from 2000 to 2005.

For babies whose mothers took folate supplements in the first trimester of pregnancy, there was an increased risk of wheeze and an increased risk of respiratory tract infections (relative risks 1.06 and 1.09, respectively), versus those without exposure, the data revealed. There was also a higher risk of hospitalizations due to lower respiratory tract infections (relative risk 1.24), the researchers found.

"Synthetic folic acid, the most commonly used folate form in supplements, is different from folates in food, and may act differently than natural occurring folates. Absorption of [synthetic folic acid] is a saturable process, and regular intake of folic acid supplements will in many subjects result in circulating unmetabolized folic acid, which may have possible effects on immune cells," the authors write. "[Our] findings are in agreement with the hypothesis that early childhood respiratory health may be affected by the possible epigenetic influences of methyl donors in maternal diet during pregnancy."

Håberg SE, London Dr SJ, Stigum H, et al. Folic acid supplements in pregnancy and early childhood respiratory health. Arch Dis Child. Published online at doi:10.1136/adc.2008.142448