Vitamin D insufficiency is prevalent and vitamin D is inversely associated with parathyroid hormone and calcitriol in pregnant adolescents

Abstract

Few large studies have assessed changes in calcitropic hormones and maternal 25(OH)D status across pregnancy, and how this may impact maternal bone turnover and neonatal hormone status. We aimed to identify determinants of 25(OH)D, PTH, and calcitriol across pregnancy in a longitudinal study of 168 pregnant adolescents (≤18 y of age). Maternal 25(OH)D, PTH, and calcitriol were assessed at mid-gestation (~26 weeks), delivery, and in cord blood. Data were related to measures of maternal anthropometrics, dietary intake, physical activity, and bone turnover markers. Approximately 50% of teens and their infants had serum 25(OH)D ≤20 ng/mL; 25(OH)D was lower in African Americans versus Caucasians (p<0.001). PTH increased across gestation (p<0.001). Elevated PTH (≥60 pg/mL) was detected in 25% of adolescents at delivery, and was associated with increased concentrations of serum NTX (p=0.028). PTH and calcitriol did not significantly differ across the range of Ca intakes consumed (257-3220 mg/day). In the group as a whole, PTH was inversely associated with 25(OH)D in maternal circulation at mid-gestation (p=0.023) and at delivery (p=0.019). However, when the cohort was partitioned by 25(OH)D status, this relationship was only present in those with 25(OH)D ≤20 ng/mL, suggestive of a threshold below which 25(OH)D impacts PTH during pregnancy. Mid-gestation 25(OH)D was inversely associated with calcitriol at delivery (p=0.023), irrespective of Ca intake. Neonatal PTH and calcitriol were significantly lower than (p<0.001), but unrelated to maternal concentrations. These findings indicate that maternal 25(OH)D status plays a role in calcitropic hormone regulation in pregnant adolescents.

Effect of calcium plus vitamin D supplementation during pregnancy in Brazilian adolescent mothers: a randomized, placebo-controlled trial

“…At midpregnancy, 43% of mothers had a serum 25(OH)D concentration ,50 nmol/L (28), which was consistent with the high prevalence of vitamin D insufficiency during pregnancy and lactation worldwide (29,30), especially in adolescents (19,20,32). Although serum 25(OH)D tended to be higher in the supplemented group than in the placebo group at postpartum measurements (P = 0.08), the prevalence of a serum 25(OH)D concentration ,50 nmol/L remained high at 20 wk postpartum in both groups (43% in the placebo group and 35% in the calcium plus vitamin D group).…”

“…In adolescent mothers, maternal vitamin D insufficiency was associated with higher serum PTH (19,20), higher bone resorption during pregnancy (31), and lower maternal bone mineral status during lactation (19). In the current study, at midpregnancy and during lactation, no associations between maternal serum 25(OH)D and serum PTH or bone mineral status were shown.…”

“…Moreover, there is evidence that vitamin D insufficiency is highly prevalent in adolescent mothers (19,20). Therefore, testing the effect of calcium supplementation during adolescent pregnancy on maternal bone mass also requires the provision of supplemental vitamin D to ensure that vitamin D status is not a limiting factor.…”

Deficiencia de vitamina D en madres y neonatos mexicanos

“…En la presente investigación no se encontraron diferencias entre los valores sanguíneos de las madres adolescentes y de las madres adultas. Lo anterior difiere de lo reportado en la literatura en otros grupos poblacionales, en donde las madres adolescentes tienen una mayor pérdida de masa ósea desde el 26 (13) 49 (26) 95 (50) 21 (11) 9 (13) 18 (26) 35 (51) 7 (10) 17 (14) 31 (25) comienzo del embarazo hasta la sexta semana posparto, indicando que la prevalencia de deficiencia de vitamina D en ellas es mayor 13,[23][24][25] . En nuestro estudio se documentó que la tercera parte de las madres presentaron sobrepeso u obesidad al inicio del embarazo, lo cual se incrementó significativamente al final del mismo.…”

Vitamin D Status Affects Serum Metabolomic Profiles in Pregnant Adolescents

“…Detailed data on vitamin D metabolism, including 25(OH)D, parathyroid hormone, 1,25-dihydroxyvitamin D, serum total calcitriol, vitamin D receptor, placental cytochrome P (CYP) 27B1 and CYP24A1, interleukin-6 (IL-6), leptin, and osteoprotegerin, have been previously published. 8,15,[44][45][46][47][48] …”