Abstract
There is currently little information on changes in vitamin D status during pregnancy and its predictors. The aim was to study the determinants of change in vitamin D status during pregnancy and of vitamin D deficiency (<30 nmol/L) in early pregnancy. Blood was drawn in the first (T1) and third trimester (T3). Serum 25-hydroxyvitamin D (25(OH)D) (N = 1985) was analysed by liquid chromatography tandem-mass spectrometry. Season-corrected 25(OH)D was calculated by fitting cosine functions to the data. Mean (standard deviation) 25(OH)D was 64.5(24.5) nmol/L at T1 and 74.6(34.4) at T3. Mean age was 31.3(4.9) years, mean body mass index (BMI) was 24.5(4.2) kg/m2 and 74% of the women were born in Sweden. Vitamin D deficiency was common among women born in Africa (51%) and Asia (46%) and prevalent in 10% of the whole cohort. Determinants of vitamin D deficiency at T1 were of non-North European origin, and had less sun exposure, lower vitamin D intake and lower age. Season-corrected 25(OH)D increased by 11(23) nmol/L from T1 to T3. The determinants of season-corrected change in 25(OH)D were origin, sun-seeking behaviour, clothing style, dietary vitamin D intake, vitamin D supplementation and recent travel <35° N. In conclusion, season-corrected 25(OH)D concentration increased during pregnancy and depended partly on lifestyle factors. The overall prevalence of vitamin D deficiency was low but common among women born in Africa and Asia. Among them, the determinants of both vitamin D deficiency and change in season-corrected vitamin D status were fewer, indicating a smaller effect of sun exposure.
Highlights
During the past decade, vitamin D has received increasing attention and has been associated with health benefits in addition to its recognized effects on bone health
Our findings show that the prevalence of vitamin D deficiency is 10% overall and 2% among women born in North Europe
We found that determinants of change in season-corrected vitamin D status were related to sun exposure, vitamin D intake and origin
Summary
Vitamin D has received increasing attention and has been associated with health benefits in addition to its recognized effects on bone health. One of these areas of interest is vitamin D status during pregnancy. Poor maternal vitamin D status during pregnancy is associated with lower bone mineral density and muscle strength in the infant [2]. Nutrients 2016, 8, 655 been associated with pregnancy complications such as preeclampsia [3], premature birth [4] and infants born small for gestational age [5]. We have previously shown that 25-hydroxyvitamin D (25(OH)D) concentrations in the third trimester and changes in
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