Vitamin D and corticotropin-releasing hormone in term and preterm birth: potential contributions to preterm labor and birth outcome

Abstract

Background: Poor maternal vitamin D status and elevated circulating corticotropin-releasing hormone (CRH) are associated with preterm birth. It is not known if these risk factors are independent or interrelated. Both are associated with inflammation.

Methods: We measured maternal circulating 25-hydroxyvitamin D (25-OH-D) and CRH from 97 samples collected from 15 early-preterm, 31 late-preterm, 21 early-term, and 30 term births. The potential involvement of vitamin D in the regulation of inflammation was evaluated by Q-PCR in human uterine smooth muscle (UTSM) cell line.

Results: Maternal 25-OH-D was lowest in early-preterm births (22.9 ± 4.2 ng/ml versus 34.4 ± 1.4 ng/ml; p = .029). Circulating CRH was high in early-preterm births (397 ± 30 pg/ml). Late-preterm (304 ± 13 pg/ml) and early-term births (347 ± 17 pg/ml) were not different from term births (367 ± 19 pg/ml), after accounting for gestational age. Maternal circulating 25-OH-D and CRH were not associated in term births. In preterm births, 25-OH-D below 30 ng/ml was associated with higher CRH. Vitamin D treatment of UTSM significantly reduced mRNA for leptin and IL-6 receptors. Deletion of vitamin D receptor from UTSM promoted the expression of the cox2 inflammatory marker.

Conclusion: Early-preterm birth showed a syndrome of high maternal CRH and low vitamin D status.

Keywords:

• African American
• APGAR
• inflammation
• pregnancy

Disclosure statement

The authors report no conflicts of interest.

Additional information

Funding

Partial support provided by grant UA6MC19010 from the Maternal Child Health Bureau of the Health Resources and Services Administration (HRSA). HRSA had no involvement in the planning, analysis, or write up for this research.