title: Vitamin D expenditure is not altered in pregnancy and lactation despite changes in vitamin D metabolite concentrations.
abstract: Pregnancy and lactation are associated with changes in vitamin D and calcium metabolism but the impact of these changes on vitamin D expenditure is unknown. We measured plasma 25(OH)D3 half-life with a stable-isotope tracer and investigated relationships with vitamin D metabolites in pregnant, lactating and 'non-pregnant, non-lactating' (NPNL) women. Vitamin D metabolites, vitamin D binding protein (DBP), PTH and 25(OH)D3 half-life were measured in third-trimester pregnant women (n22) and repeated during lactation 12 weeks post-partum (n14) and twice in NPNL women (n23 and n10, respectively) in rural Gambia where calcium intakes are low with little seasonality in UVB-exposure. 25(OH)D3 half-life was not significantly different between groups (mean(SD): 20.6(6.8), 22.6(7.7), 18.0(4.7) and 17.7(9.5) days in pregnant, lactating and NPNL women, respectively). Plasma 25(OH)D3, 1,25(OH)2D, and DBP were higher in pregnancy, and calculated free-25(OH)D3 and PTH were lower (P < 0.05). In lactation, 25(OH)D3 and 24,25(OH)2D3 were lower compared to pregnant (P < 0.001, P = 0.02) and NPNL women (P = 0.04, P = 0.07). Significant associations were observed between half-life and 25(OH)D3 (+ve) in pregnancy, and in all groups between 25(OH)D3 and free-25(OH)D3 (+ve) and PTH and 25(OH)D3 (-ve) (P < 0.0001). These data suggest that adaptive changes in pregnancy and lactation occur that prevent pronounced changes in vitamin D expenditure.
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge, CB1 9NL, UK.|MRC Keneba, MRC Unit, Banjul, The Gambia.
authors.forename: Kerry S
authors.initials: KS
authors.lastname: Jones
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge, CB1 9NL, UK.
authors.forename: Shima
authors.initials: S
authors.lastname: Assar
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge, CB1 9NL, UK.|MRC Keneba, MRC Unit, Banjul, The Gambia.
authors.forename: Ann
authors.initials: A
authors.lastname: Prentice
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge, CB1 9NL, UK.
authors.forename: Inez
authors.initials: I
authors.lastname: Schoenmakers
mesh_terms: D000328:Adult; D002112:Calcifediol / Q000097:blood; D003430:Cross-Sectional Studies; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D005714:Gambia; D006207:Half-Life; D006706:Homeostasis; D006801:Humans; D007774:Lactation / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000097:blood; D011247:Pregnancy / Q000378:metabolism*; D011446:Prospective Studies; D013472:Sunlight; D014807:Vitamin D / Q000378:metabolism*; D014809:Vitamin D-Binding Protein / Q000097:blood; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D014809:Vitamin D-Binding Protein; D014807:Vitamin D; D002112:Calcifediol