Maternal vitamin D status and childhood asthma, wheeze, and eczema: A systematic review and meta-analysis

Background: Maternal vitamin D status has been reported to be associated with childhood allergic diseases. However, this association remains to be fully elucidated. Methods: A systematic review and meta-analysis was conducted using prospective cohort studies that examined the association between maternal vitamin D status and childhood allergic diseases including wheeze, eczema and asthma. We searched electronic databases of PubMed, EMBASE, the Cochrane library, the Wanfang (Chinese) database, the VIP (Chinese) database, and Chinese National Knowledge Infrastructure (CNKI) up to August 2014. Odds ratios and 95% confidence intervals (CIs) from individual studies were synthesized using a fixed effects model. Results: Four studies on the association between maternal vitamin D status and childhood asthma (3666 mother-child pairs), four studies on the association between maternal vitamin D status and childhood wheeze (2225 mother-child pairs) and three papers on the association between maternal vitamin D status and childhood eczema (2172 mother-child pairs) met our inclusion criteria. Maternal vitamin D status during pregnancy was associated with childhood eczema (pooled OR=0.904, 95% CI=0.831-0.983). However, the meta-analysis showed no statistical association between maternal vitamin D status and childhood asthma (pooled OR=0.981, 95% CI=0.944-1.019) or childhood wheeze (pooled OR=0.995, 95% CI=0.982-1.009). Conclusions: Our meta-analysis found that lower maternal vitaminDduring pregnancy was associated with an increased risk of childhood eczema but was not associated with childhood asthma or wheeze. The role of maternal vitaminDas an important protective factor for the development of childhood eczema remains to be elucidated.