Main findings
This study shows that 25(OH)D levels in umbilical cord blood are higher than levels in maternal blood. The correlation between the maternal and umbilical cord blood is solid and consistent over the range of maternal levels. Only the supplementation dose significantly impacted the maternal 25(OH)D level. Low maternal 25(OH)D levels were not associated with a risk for premature labor, premature rupture of the membranes, diabetes, or low AS.