Meta-analyses of r and omized controlled trials ( RCTs ) document that physiological vitamin D supplementation during pregnancy is safe and improves vitamin D and calcium status , thereby protecting skeletal health .
Although certain RCTs and /or meta-analyses reported some other beneficial effects , it is still not clear whether vitamin D supplementation  improves fertility or decreases the risk of adverse pregnancy outcomes such as low birth weight , pre-eclampsia and neonatal mortality , or reduces wheeze/asthma in the infants .
Vitamin D deficiency is common and there exists a huge gap between recommended dietary vitamin D intakes and the poor vitamin D supply in the general population .
While vitamin D is important for musculoskeletal health , there are accumulating data suggesting that vitamin D may also be important for fertility , pregnancy outcomes and lactation .
Significant changes in vitamin D metabolism during pregnancy such as increased production of the " active vitamin D hormone " calcitriol support the important role of vitamin D in this setting .
Observational studies show that vitamin D deficiency is a risk marker for reduced fertility and various adverse pregnancy outcomes and is associated with a low vitamin D content of breast milk .
Nevertheless , vitamin D supplementation in pregnant women is frequently required to achieve a sufficient vitamin D status as recommended by nutritional vitamin D guidelines .
25-Hydroxyvitamin D in pregnancy and genome wide cord blood DNA methylation in two pregnancy cohorts (MoBa and ALSPAC)
Highlights • Pregnancy vitamin D and cord blood DNA methylation compared in 1416 infants.• Associations tested in two large prospect i ve cohort studies , MoBa and ALSPAC.• Similarly for offspring health outcomes and vitamin D  , no convincing associations
Meta-analyses of r and omized controlled trials ( RCTs ) document that physiological vitamin D supplementation during pregnancy is safe and improves vitamin D and calcium status , thereby protecting skeletal health .
Although certain RCTs and /or meta-analyses reported some other beneficial effects , it is still not clear whether vitamin D supplementation  improves fertility or decreases the risk of adverse pregnancy outcomes such as low birth weight , pre-eclampsia and neonatal mortality , or reduces wheeze/asthma in the infants .
Vitamin D deficiency is common and there exists a huge gap between recommended dietary vitamin D intakes and the poor vitamin D supply in the general population .
While vitamin D is important for musculoskeletal health , there are accumulating data suggesting that vitamin D may also be important for fertility , pregnancy outcomes and lactation .
Significant changes in vitamin D metabolism during pregnancy such as increased production of the " active vitamin D hormone " calcitriol support the important role of vitamin D in this setting .
Observational studies show that vitamin D deficiency is a risk marker for reduced fertility and various adverse pregnancy outcomes and is associated with a low vitamin D content of breast milk .
Nevertheless , vitamin D supplementation in pregnant women is frequently required to achieve a sufficient vitamin D status as recommended by nutritional vitamin D guidelines .