Maternal vitamin D insufficiency is associated with childhood rickets and longer-term problems including schizophrenia and type 1 diabetes(Reference Holick1). Whilst maternal vitamin D insufficiency is common in mothers with highly-pigmented skin(Reference van der Meer, Karamali and Boeke2), little is known about the vitamin D status of Caucasian pregnant women.
The aim of the present study was to investigate vitamin D status in Caucasian pregnant women and non-pregnant age-matched controls living at 54°N–55°N. In a longitudinal study plasma 25-hydroxyvitamin D (25(OH)D) was assessed in ninety-nine pregnant women at 12, 20 and 35 weeks of gestation and in thirty-eighty non-pregnant women sampled concurrently.
Plasma 25(OH)D concentrations were lower in pregnant women compared with non-pregnant women at 20 and 35 weeks of gestation (P<0.0001). The percentage of pregnant women below the various cut-off values for vitamin D deficiency and insufficiency are presented in the Table.
* Data are cumulative.
While severe vitamin D deficiency (25(OH)D<12.5 nmol/l) was not apparent in the non-pregnant controls at any time-point, >95% of non-pregnant women were classified as insufficient at each time-point, assuming a cut-off of vitamin D insufficiency of <80 nmol/l. Vitamin D status was higher in pregnant women who reported taking multivitamin supplements at 12 (P<0.0001), 20 (P=0.001) and 35 (P=0.001) weeks of gestation than in pregnant non-supplement users; however, supplements did not prevent insufficiency (25(OH)D>50 nmol/l).
In summary, there is a high prevalence of both vitamin D deficiency and insufficiency in pregnant Caucasian women considered at low risk of vitamin D deficiency living at 54°N–55°N. Women reporting multivitamin supplement usage during pregnancy did have higher vitamin D status, but many remained vitamin D insufficient. Suboptimal vitamin D status has important consequences for maternal and neonatal health, and thus, further research is needed to determine the dietary vitamin D intake required to maintain vitamin D sufficiency during pregnancy and to underpin guidelines for supplement use during pregnancy.
