Impact of vitamin D on pregnancy-related disorders and on offspring outcome

•A high incidence of vitamin D deficiency in pregnant women is found by many observational studies around the world.•Vitamin D deficiency during pregnancy is associated with a higher risk for preeclampsia, gestational diabetes mellitus and other gestational diseases. Moreover, observational evidence links low maternal vitamin D levels during pregnancy with adverse fetal birth outcomes and long term health of the offspring.•The number of high quality studies and meta-analysis is still too limited to draw conclusions regarding a causal role of vitamin D for the etiology of adverse pregnancy outcomes.•Further investigation is required to better understand the effects of vitamin D for the prevention of pregnancy-associated diseases and recommendations for vitamin D supplementation by the public health authorities need to be substantiated with empirical robust data.•There is increasing evidence of the importance of maternal vitamin D status for the health of mother and offspring. Prevention of vitamin D deficiency in pregnant women and their children therefore displays an important global goal. Observational studies from all over the world continue to find high prevalence rates of vitamin D insufficiency and deficiency in many populations, including pregnant women. Beyond its classical function as a regulator of calcium and phosphate metabolism, vitamin D elicits numerous effects in the human body. Current evidence highlights a vital role of vitamin D in mammalian gestation. During pregnancy, adaptations in maternal vitamin D metabolism lead to a physiologic increase of vitamin D levels, mainly because of an increased renal production, although other potential sources like the placenta are being discussed. A sufficient supply of mother and child with calcium and vitamin D during pregnancy ensures a healthy bone development of the fetus, whereas lack of either of these nutrients can lead to the development of rickets in the child. Moreover, vitamin D insufficiency during pregnancy has consistently been associated with adverse maternal and neonatal pregnancy outcomes. In multitudinous studies, low maternal vitamin D status was associated with a higher risk for preeclampsia, gestational diabetes mellitus and other gestational diseases. Likewise, several negative consequences for the fetus have been reported, including fetal growth restriction, increased risk of preterm birth and a changed susceptibility for later-life diseases. However, study results are diverging