Maternal folic acid use during pregnancy, MTHFR polymorphism, and child's lung function and asthma

Abstract

Background

Folic acid supplement use during pregnancy might affect childhood respiratory health, potentially mediated by methylenetetrahydrofolate-reductase polymorphism C677T (MTHFR-C677T) carriership.

Objectives

We examined the associations of maternal folic acid supplement use and folate, vitamin B₁₂ and homocysteine concentrations during pregnancy with childhood lung function and asthma.

Methods

This study was embedded in a population-based prospective cohort study among 5,653 children. Folic acid supplement use was assessed by questionnaires. Folate, vitamin B₁₂ and homocysteine plasma concentrations were measured in early pregnancy and at birth. At age 10 years, forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), FEV₁/FVC, forced expiratory flow between 25% and 75% (FEF_25-75), at 75% of FVC (FEF₇₅), and asthma were examined.

Results

Maternal folic acid supplement use during pregnancy was associated with higher childhood FEV₁ and FVC and with a lower FEV₁/FVC, compared with no folic acid supplement use. Among mothers carrying MTHFR-C677T variants, preconceptional start of folic acid supplement use was associated with lower FEV₁/FVC (-0.17 (-0.32, -0.02)) and FEF_25-75 (-0.24 (-0.40, -0.07)). Among children carrying MTHFR-C677T wildtype, a higher vitamin B₁₂ level at birth was associated with a lower FEV₁ (-0.07 (-0.12, -0.01)) and FVC (-0.09 (-0.15, -0.04). Folate and homocysteine concentrations were not consistently associated with lower childhood lung function or asthma.

Conclusions

Preconceptional start of maternal folic acid supplement use and higher vitamin B₁₂ concentrations at birth might adversely affect childhood lung function depending on MTHFR-C677T carriership. The clinical implications need to be evaluated.

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