Antenatal vitamin C and E supplementation does not reduce infant wheeze risk
MedWire News: Results from a UK study suggest that vitamin C and E supplementation during pregnancy does not reduce the risk for wheeze in young children.
Writing in the journal Thorax, Anne Greenough (King's College Hospital, London, UK) and colleagues explain: "Prenatal antioxidant exposure might… influence fetal lung growth and development and hence reduce postnatal respiratory morbidity."
Furthermore, they say that observational birth cohort studies have indicated that a lower maternal intake of vitamin E in pregnancy is associated with a higher prevalence of early childhood wheezing and later asthma.
To investigate whether antenatal vitamin C and E supplementation is associated with improved respiratory outcomes in young children, the team studied 752 children born to 643 women at increased risk for pre-eclampsia due to the presence of one or more risk factors.
All of the children were at heightened risk for fetal growth restriction and premature delivery, which are in turn associated with an increased risk for respiratory problems.
In total, 330 women were assigned to take vitamin C and E supplements and 313 were assigned to take placebo from the second trimester of pregnancy.
Maternal questionnaires were used to assess respiratory outcomes among the children in the first 2 years of life. Healthcare utilization and associated costs were also evaluated in a subgroup 54 women and their infants in the vitamin group and 45 women and their infants in the placebo group.
Of the 386 children born to women who took the vitamin supplements during pregnancy, 3.9% suffered from wheezing more than once a week and 23.3% had suffered from wheezing at some point in the first 12 months of life compared with 4.6% and 28.1%, respectively, of the 366 children born to women who took placebo.
However, there were no significant differences in frequent and ever wheezing rates between the two groups in the second year of life, at 13.2% and 86.8%, respectively, among children in the vitamin group, and a corresponding 10.1% and 85.8% among those in the placebo group.
The researchers found that mothers and children in the vitamin group had an average 2.6 times more accident and emergency/outpatient visits and 3.2 times more GP visits than those in the placebo group, and the associated care costs were significantly higher in the vitamin versus placebo group.
Greenough and team conclude: "High-dose vitamins C and E supplementation daily from the second trimester of pregnancy did not improve respiratory outcome in the offspring.
"Furthermore, our results suggest that such high-dose prenatal supplementation is disadvantageous, at least in women at high risk of pre-eclampsia, as it is associated with increased healthcare utilization and cost of care for infants."
They add: "These deleterious consequences should be considered in the context of recent evidence from randomized trials of higher adult mortality associated with vitamin supplementation."
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By Mark Cowen