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

Bridget E. Young, Thomas J. McNanley, Elizabeth M. Cooper, Allison W. McIntyre, Frank Witter, Z. Leah Harris, Kimberly O. O'Brien*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Few large studies have assessed changes in calcitropic hormones and maternal 25-hydroxyvitamin D (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, parathyroid hormone (PTH), and calcitriol across pregnancy in a longitudinal study of 168 pregnant adolescents (≤18 years 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 a;circ 20 ng/mL; 25(OH)D was lower in African Americans versus whites (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 N-telopeptide (NTX) (p=0.028). PTH and calcitriol did not significantly differ across the range of Ca intake consumed (257-3220 mg/d). 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.

Original languageEnglish (US)
Pages (from-to)177-186
Number of pages10
JournalJournal of Bone and Mineral Research
Volume27
Issue number1
DOIs
StatePublished - Jan 2012

Keywords

  • 1,25-dihydroxyvitamin D
  • 25-hydroxyvitamin D
  • Adolescence
  • Parathyroid hormone
  • Pregnancy

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Orthopedics and Sports Medicine

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