Global summary of maternal and newborn vitamin D status - a systematic review.

Pregnant women and newborns are at increased risk of vitamin D deficiency. Our objective was to create a global summary of maternal and newborn vitamin D status. We completed a systematic review (1959-2014) and meta-analysis of studies reporting serum 25-hydroxyvitamin D [25(OH)D] concentration in maternal and newborn populations. The 95 identified studies were unevenly distributed by World Health Organization (WHO) region: Americas (24), European (33), Eastern Mediterranean (13), South-East Asian (7), Western Pacific (16) and African (2). Average maternal 25(OH)D concentrations (nmol L(-1) ) by region were 47-65 (Americas), 15-72 (European), 13-60 (Eastern Mediterranean), 20-52 (South-East Asian), 42-72 (Western Pacific) and 92 (African). Average newborn 25(OH)D concentrations (nmol L(-1) ) were 35-77 (Americas), 20-50 (European), 5-50 (Eastern Mediterranean), 20-22 (South-East Asian), 32-67 (Western Pacific) and 27-35 (African). The prevalences of 25(OH)D <50 and <25 nmol L(-1) by WHO region in pregnant women were: Americas (64%, 9%), European (57%, 23%), Eastern Mediterranean (46%, 79%), South-East Asian (87%, not available) and Western Pacific (83%, 13%). Among newborns these values were: Americas (30%, 14%), European (73%, 39%), Eastern Mediterranean (60%, not available), South-East Asian (96%, 45%) and Western Pacific (54%, 14%). By global region, average 25(OH)D concentration varies threefold in pregnant women and newborns, and prevalence of 25(OH)D <25 nmol L(-1) varies eightfold in pregnant women and threefold in newborns. Maternal and newborn 25(OH)D concentrations are highly correlated. Addressing vitamin D deficiency in pregnant women and newborns should be a global priority. To protect children from the adverse effects of vitamin D deficiency requires appropriate interventions during both pregnancy and childhood.