Folic acid supplements in pregnancy and early childhood respiratory health

Siri E Håberg ^1*, Stephanie J London Dr², Hein Stigum ¹, Per Nafstad ³ and Wenche Nystad ⁴

¹ Norwegian Insitute of Public Health, Norway
² NIEHS, United States
³ Medical Faculty, University of Oslo, Norway
⁴ Division of Epidemiology, Norway

^* To whom correspondence should be addressed. E-mail: siri.haberg{at}fhi.no.

Accepted 26 September 2008

Abstract

Background: Folate supplementation is recommended for pregnant women to reduce the risk of congenital malformations. Maternal intake of folate supplements during pregnancy might also influence childhood immune phenotypes via epigenetic mechanisms.

Objective: To investigate the relationship between folate supplements in pregnancy and risk of lower respiratory tract infections and wheeze in children through 18 months of age.

Methods: In the Norwegian Mother and Child Cohort Study, questionnaire data collected at several time points in pregnancy and after birth, from 32,077 children born between 2000 and 2005, were used to assess effects of folate supplements during pregnancy on respiratory outcomes up to 18 months of age, accounting for other supplements in pregnancy and supplementation in infancy.

Results: Folate supplements in the first trimester were associated with increased risk of wheeze and respiratory tract infections up to 18 months of age. Adjusting for exposure later in pregnancy and in infancy, the relative risk of wheeze for children exposed to folic acid supplements in the first trimester was 1.06 (95% confidence interval: 1.03, 1.10), for lower respiratory tract infections the relative risk was 1.09 (95% confidence interval: 1.02, 1.15), and for hospitalizations for lower respiratory tract infections the relative risk was 1.24 (95% confidence interval: 1.09, 1.41).

Conclusions: Folic acid supplements in pregnancy were associated with a slightly increased risk of wheeze and lower respiratory tract infections up to 18 months of age. Results support possible epigenetic influences of methyl donors in maternal diet during pregnancy on respiratory health in children.