Vitamin D during pregnancy reduces risk of childhood asthma by 13 percent – meta-analysis

Created December 2016

Maternal vitamin D status during pregnancy and risk of childhood asthma a meta-analysis of prospective studies

Molecular Nutrition & Food Research, Accepted 16 Dec 2016, DOI: 10.1002/mnfr.20160065

Huihui Song, Lei Yang, Chongqi Jia

The study is behind a $38 paywall Probably this, like most other meta-analyses, did not consider Vitamin D dose size     Thus they would assign the same importance to 400 IU as 6,000 IU Speculate: A good level of vitamin D (> 40 ng with >6,000 IU) would reduce childhood asthma by >40 % See also VitaminDWiki * Asthma in 3 year olds decreased somewhat with 4,000 IU during pregnancy – RCT Jan 2016 * by 6%, but not statistically significant * Low vitamin D during pregnancy associated with four health problems in children – Jan 2015 * Just 700 IU of vitamin D during pregnancy reduced rate of asthma at age 7 by 26 percent – Oct 2013 * Overview Asthma and Vitamin D * Asthma reduced 60 percent with vitamin D supplementation – meta-analysis 2014, 2015 * Child supplemented, not during pregnancy * If high vitamin D during pregnancy the child is [tiki-download_file.php?fileId=1541] Healthy pregnancies need lots of vitamin D - many benefits {include}

Scope

Mounting evidence suggests that maternal vitamin D status during pregnancy may be associated with development of childhood asthma, but the results are still inconsistent. A dose-response meta-analysis was performed to quantitatively summarize evidence on the association of maternal vitamin D status during pregnancy with the risk of childhood asthma.

Methods and results

A systematic search was conducted to identify all studies assessing the association of maternal 25-hydroxyvitamin D (25(OH)D) during pregnancy with risk of childhood asthma. The fixed or random-effect model was selected based on the heterogeneity test among studies. Nonlinear dose–response relationship was assessed by restricted cubic spline model.

Fifteen prospective studies with 12,758 participants and 1,795 cases were included in the meta-analysis. The pooled RR of childhood asthma comparing the highest versus lowest category of maternal 25(OH)D levels was 0.87 (95% confidence interval, CI, 0.75-1.02). For dose–response analysis, evidence of a U-shaped relationship was found between maternal 25(OH)D levels and risk of childhood asthma (P-nonlinearity = 0.02), with the lowest risk at approximately 70 nmol/L of 25(OH)D.

Conclusion

This dose–response meta-analysis suggested a U-shaped relationship between maternal blood 25(OH)D levels and risk of childhood asthma. Further studies are needed to confirm the association.

Tags: Breathing Meta-analysis Pregnancy