05 Jul 2018 --- One in three pregnant women in Norway has a vitamin D deficiency by the end of her pregnancy, a study published in PLOS One has shown. This number spikes in Norway’s dark winter months, which often do not provide enough sunlight for the sunshine vitamin to form, leading to rates of vitamin D deficient pregnant women reaching 50 percent. The study, which included 855 pregnant Norwegian women, highlights how many women are not taking government advice on vitamin D supplementation and calls for further action.