Vitamin D status in Iranian pregnant women and newborns: a systematic review and meta-analysis study

Background: Vitamin D deficiency is a common health problem worldwide. The present study was conducted to assess the vitamin D status in Iranian pregnant women and newborns. Methods: A systematic review was conducted following PRISMA guidelines. The Scopus, PubMed, Science Direct, Cochrane, Web of Science, CINAHL, Magiran, Iranmedex, SID, Medlib, IranDoc databases, and Google Scholar were searched until 2017. The data were combined using random effects model. p < 0.05 was considered significant. Results: In 23 studies including 6,127 Iranian pregnant women were eligible for inclusion. The prevalence of vitamin D deficiency based on cutoff points of 10, 20, and 30 ng/ml was estimated to be 42.42% (95%CI: 26.90-57.93), 55.84% (95%CI: 31.75-79.93) and 80.82% (95%CI: 71.20-90.45), respectively. The mean 25-hydroxyvitamin D [25(OH)D] concentration was estimated to be 15.69 ng/ml (95% CI: 14.39-17.00) in pregnant women. The mean 25(OH)D concentration was estimated to be 14.97 ng/ml (95% CI: 10.63-19.31) in Iranian newborns. The difference in mean 25(OH)D concentration between pregnant women and their newborns was significant (p = 0.0002). Conclusions: Vitamin D status in Iranian pregnant women and newborns are critical. Therefore, paying attention to the issue of vitamin D deficiency in this group should be a health priority in Iran.