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 .
Maternal Serum and Breast Milk Vitamin D Levels: Findings from the Universiti Sains Malaysia Pregnancy Cohort Study
Background Vitamin D deficiency has become a global health issue in pregnant women . This study aim ed to assess the adequacy of maternal vitamin D status by measuring maternal serum and breast milk 25-hydroxyvitamin D [ 25(OH)D ] levels and to determine the association between maternal serum and milk 25(OH)D levels . Methods Data was obtained from the Universiti Sains Malaysia Pregnancy Cohort Study . This study was conducted from April 2010 to December 2012 in the state of Kelantan , Malaysia . Blood sample s from pregnant women aged 19 to 40 years were drawn in the second and third trimesters of pregnancy , while breast milk sample s at delivery , 2 , 6 and 12 months postpartum were collected to analyze for 25(OH)D levels . A total of 102 pregnant women were included in the analysis . Results Vitamin D deficiency [ 25(OH)D < 50 nmol/L ] was detected in 60 % and 37 % of women in the second and third trimesters of pregnancy , respectively . There were 6 % and 23 % of women who reached normal level of vitamin D status in the second trimester and the third trimester , respectively . Multivitamin intakes during pregnancy were significantly associated with higher serum 25(OH)D levels in the second trimester ( β = 9.16 , p = 0.005 ) and the third trimester ( β = 13.65 , p = 0.003 ) . 25(OH)D levels in breast milk during the first year of lactation ranged from 1.01 to 1.26 nmol/L. Higher maternal serum 25(OH)D level in the second trimester of pregnancy was associated with an elevated level of 25(OH)D in breast milk at delivery ( β = 0.002 , p = 0.026 ) . Conclusions This study shows that high proportions of Malay pregnant women are at risk of vitamin D deficiency . Maternal vitamin D status in the second trimester of pregnancy was found to influence vitamin D level in breast milk at delivery
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 .