Changes in plasma concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D during pregnancy: a Brazilian cohort

• DOI: 10.1007/s00394-017-1389-z
• Publication Date: 2017-03-28T08:15:58Z
• Authors: Amanda C. Cunha F...; Paula Guedes Cocate; Amanda R. Amorim ...; Ana Beatriz Franc...; Dayana R. Farias; Maria Beatriz Tri...; Alex Brito; Lindsay H. Allen; Rana R. Mokhtar; Michael F. Holick; Gilberto Kac
• Keywords: Adult; Vitamin D; pregnancy; micronutrients; cohort; tropical country; seasons; Cohort Studies; 03 medical and health sciences; 0302 clinical medicine; Calcitriol; Pregnancy; Prevalence; Humans; Longitudinal Studies; Prospective Studies; Vitamin D; Calcifediol; 25-Hydroxyvitamin D 2; Maternal Nutritional Physiological Phenomena; Diet; 3. Good health; Pregnancy Complications; Dietary Supplements; Ergocalciferols; Female; Seasons; Self Report; Brazil

To characterize the physiological changes in 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] throughout pregnancy.Prospective cohort of 229 apparently healthy pregnant women followed at 5th-13th, 20th-26th, and 30th-36th gestational weeks. 25(OH)D and 1,25(OH)2D concentrations were measured by LC-MS/MS. Statistical analyses included longitudinal linear mixed-effects models adjusted for parity, season, education, self-reported skin color, and pre-pregnancy BMI. Vitamin D status was defined based on 25(OH)D concentrations according to the Endocrine Society Practice Guideline and Institute of Medicine (IOM) for adults.The prevalence of 25(OH)D <75 nmol/L was 70.4, 41.0, and 33.9%; the prevalence of 25(OH)D <50 nmol/L was 16.1, 11.2, and 10.2%; and the prevalence of 25(OH)D <30 nmol/L was 2, 0, and 0.6%, at the first, second, and third trimesters, respectively. Unadjusted analysis showed an increase in 25(OH)D (β = 0.869; 95% CI 0.723-1.014; P < 0.001) and 1,25(OH)2D (β = 3.878; 95% CI 3.136-4.620; P < 0.001) throughout pregnancy. Multiple adjusted analyses showed that women who started the study in winter (P < 0.001), spring (P < 0.001), or autumn (P = 0.028) presented a longitudinal increase in 25(OH)D concentrations, while women that started during summer did not. Increase of 1,25(OH)2D concentrations over time in women with insufficient vitamin D (50-75 nmol/L) at baseline was higher compared to women with sufficient vitamin D (≥75 nmol/L) (P = 0.006).The prevalence of vitamin D inadequacy varied significantly according to the adopted criteria. There was a seasonal variation of 25(OH)D during pregnancy. The women with insufficient vitamin D status present greater longitudinal increases in the concentrations of 1,25(OH)2D in comparison to women with sufficiency.