Alterations in the vitamin D endocrine system during pregnancy: A longitudinal study of 855 healthy Norwegian women

Miriam K Gustafsson; Pål R Romundstad; Signe Nilssen Stafne; Anne-Sofie Helvik; Astrid Kamilla Stunes; Siv Mørkved; Kjell Åsmund Salvesen; Per Medbøe Thorsby; Unni Syversen

doi:10.1371/journal.pone.0195041

Alterations in the vitamin D endocrine system during pregnancy: A longitudinal study of 855 healthy Norwegian women

PLoS One. 2018 Apr 11;13(4):e0195041. doi: 10.1371/journal.pone.0195041. eCollection 2018.

Authors

Miriam K Gustafsson^{1

2}, Pål R Romundstad¹, Signe Nilssen Stafne^{1

3}, Anne-Sofie Helvik¹, Astrid Kamilla Stunes^{4

5}, Siv Mørkved^{1

5}, Kjell Åsmund Salvesen^{4

6}, Per Medbøe Thorsby⁷, Unni Syversen^{4

8}

Affiliations

¹ Department of Public Health and Nursing, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
² Division of Mental Health Care, Trondheim University Hospital (St Olavs hospital), Trondheim, Norway.
³ Clinic of Clinical Services, Trondheim University Hospital (St Olavs hospital), Trondheim, Norway.
⁴ Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
⁵ Trondheim University Hospital (St Olavs hospital), Trondheim, Norway.
⁶ Department of Obstetrics and Gynaecology, Trondheim University Hospital (St Olavs hospital), Trondheim, Norway.
⁷ Hormone Laboratory, Department of Medical Biochemistry, Oslo University Hospital, Aker sykehus, Oslo, Norway.
⁸ Department of Endocrinology, Trondheim University Hospital (St Olavs hospital), Trondheim, Norway.

Abstract

To ensure optimal calcium accrual in the fetal skeleton, a substantial rise occurs in 1,25-dihydroxyvitamin D (1,25(OH)2D), but is dependent on sufficient 25-hydroxyvitamin (25(OH)D). Large longitudinal studies addressing free 25(OH)D and 1,25(OH)2D during pregnancy are scarce. We aimed to assess levels of and relationship between 25(OH)D, 1,25(OH)2D, vitamin D-binding protein (DBP), parathyroid hormone (PTH), and free 25(OH)D during pregnancy; determinants of vitamin D status; and association between vitamin D indices or PTH and pregnancy outcomes (gestational diabetes mellitus and birthweight). Altogether 855 pregnant Norwegian Caucasian women from Trondheim and Stavanger (latitude 63°N and 58°N) were recruited; 94 were lost to follow-up. The study was originally a randomized controlled trial (2007-2009) with gestational diabetes as primary outcome. Data were collected in second and third trimester. In third trimester, 246 (34%) had vitamin D insufficiency and 52 (7%) deficiency (25(OH)D <50 and <30nmol/L, respectively). During wintertime in third trimester, 61 (47%) from Trondheim and 23 (51%) from Stavanger exhibited vitamin D insufficiency. PTH was elevated in 27 (3.7%). Estimate of change between trimesters was (95% CI): 25(OH)D -1.8 (-2.8 to -0.7) nmol/L, DBP 0.62 (0.57 to 0.66) μmol/L, calculated free 25(OH)D -1.7 (-2.0 to -1.4) pmol/L, PTH 0.81 (0.72 to 0.90) pmol/L, 1,25(OH)2D (sub-analysis) 31.4 (CI 24.7 to 38.2) pmol/L. A decrease in 1,25(OH)2D occurred in 45% of those with vitamin D deficiency, and they also exhibited lower levels than women with adequate vitamin D status. No association of vitamin D indices and PTH with pregnancy outcomes was observed. Women in Trondheim displayed lower 25(OH)D levels, despite minor latitudinal differences. Less than one-fifth adhered to the authorities' vitamin D recommendations. These findings demonstrate that hypovitaminosis D is prevalent among pregnant women living in northern latitudes, especially during the dark season, and there is an unmet need to ensure adequate vitamin D intake.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Birth Weight
Diabetes, Gestational / metabolism
Endocrine System*
Feeding Behavior
Female
Humans
Longitudinal Studies
Norway
Nutritional Status
Parathyroid Hormone / metabolism
Pregnancy / metabolism*
Pregnancy Complications
Pregnancy Trimesters
Randomized Controlled Trials as Topic
Regression Analysis
Seasons
Surveys and Questionnaires
Vitamin D / metabolism*
Vitamin D Deficiency

Substances

Parathyroid Hormone
Vitamin D

Grants and funding

The study was supported by the Liaison Committee between the Central Norway Regional Health Authority (RHA) and the Norwegian University of Science and Technology (NTNU).