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Published on: August 7, 2017
Maternal Folate Intake during Pregnancy and Childhood Asthma in a Population-based Cohort
Christine L Parr1,2, Maria C Magnus1,3,4, Øystein Karlstad1
11 Department of Mental and Physical Health and.
Insights
High folate intake during pregnancy, especially from supplements, may slightly increase a child's risk of developing asthma. This finding suggests a need to re-evaluate recommended prenatal folate levels and dietary guidelines.
Area of Science:
- Obstetrics and Gynecology
- Pediatric Allergy and Immunology
- Nutritional Epidemiology
Background:
- High folate intake during pregnancy has been debated for potential adverse effects on child asthma development.
- Previous research on this topic has yielded controversial results, necessitating further investigation.
Purpose of the Study:
- To prospectively examine the association between maternal folate intake (dietary and supplemental) during pregnancy and the risk of asthma in children at age 7.
- To provide more reliable asthma diagnoses at age 7 compared to earlier childhood assessments.
Main Methods:
- Utilized data from the Norwegian Mother and Child Cohort Study (2002-2006 births).
- Assessed maternal folate intake via a validated food frequency questionnaire.
- Defined childhood asthma based on medication dispensing records and maternal reports.
- Employed log-binomial and multinomial regression models to calculate adjusted relative risks.
Main Results:
- A higher total folate intake during pregnancy was associated with an increased risk of childhood asthma (adjusted RR 1.23; 95% CI, 1.06-1.44).
- This association remained consistent for both medication-defined and parent-reported asthma.
- Mothers with the highest folate intake consumed substantial food folate and typically took folic acid supplements at or above recommended doses.
Conclusions:
- High total folate intake in pregnancy, particularly from folic acid supplements exceeding recommended doses alongside a folate-rich diet, is linked to a slightly elevated risk of childhood asthma.
- These findings suggest a potential need to reconsider current recommendations for prenatal folate intake.
Rationale:
A potential adverse effect of high folate intake during pregnancy on children's asthma development remains controversial.
Objectives:
To prospectively investigate folate intake from both food and supplements during pregnancy and asthma at age 7 years when the diagnosis is more reliable than at preschool age.
Methods:
This study included eligible children born 2002-2006 from the Norwegian Mother and Child Cohort Study, a population-based pregnancy cohort, linked to the Norwegian Prescription Database. Current asthma at age 7 was defined by asthma medications dispensed at least twice in the year (1,901 cases; n = 39,846) or by maternal questionnaire report (1,624 cases; n = 28,872). Maternal folate intake was assessed with a food frequency questionnaire validated against plasma folate. We used log-binomial and multinomial regression to calculate adjusted relative risks with 95% confidence intervals.
Measurements And Main Results:
Risk of asthma was increased in the highest versus lowest quintile of total folate intake with an adjusted relative risk of 1.23 (95% confidence interval, 1.06-1.44) that was similar for maternally reported asthma. Mothers in the highest quintile had a relatively high intake of food folate (median, 308; interquartile range, 241-366 microg/d) and nearly all took at least 400 microg/d of supplemental folic acid (median, 500; interquartile range, 400-600 microg/d).
Conclusions:
In this large prospective population-based cohort with essentially complete follow-up, pregnant women taking supplemental folic acid at or above the recommended dose, combined with a diet rich in folate, reach a total folate intake level associated with a slightly increased risk of asthma in children.
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