Poor vitamin D status and the risk of maternal depression: a dose-response meta-analysis of observational studies.

Objective The association between 25-hydroxyvitamin D (25(OH)D) and maternal depression (MD) is deemed to be inconclusive. The current analysis aimed to quantify the relationship between 25(OH)D serum concentrations, the main indicator of vitamin D nutritional status, and MD. Design Dose-response meta-analysis. Setting A systematic search in PubMed, Embase and Web of Science from inception to June 2019. Participants Relevant observational studies reporting risk estimates and 95 % CI of random effects for 25(OH)D concentration on MD were identified. Results Twelve observational studies with thirteen independent reports involving 10 317 pregnant women were included. Compared with the lowest category of 25(OH)D, the pooled OR for the highest category of MD was 0·49 (95 % CI 0·35, 0·63); a high heterogeneity was observed (P = 0·001, I2 = 82·1 %). A non-linear association between 25(OH)D and MD was found (P for non-linearity = 0·001); the dose-response analysis indicated that the lowest pooled OR was at blood 25(OH)D concentrations of 90-110 nmol/l. Subgroup analyses suggested a stronger association between 25(OH)D and MD in summer time (OR 0·25, 95 % CI 0·08, 0·43) than in other seasons (OR 0·68, 95 % CI 0·52, 0·83) (P for interaction = 0·008). A visual inspection of funnel plot and Begg's and Egger's tests did not indicate any evidence of publication bias. Conclusions Low circulating 25(OH)D is associated with MD, and our analysis suggests that they influence each other. Further randomised controlled trials would be needed to determine the direction of causation.