Does antenatal cholecalciferol supplementation affect the mode or timing of delivery? Post hoc analyses of the MAVIDOS randomized controlled trial

Rebecca J. Moon, Stefania D'Angelo, Sarah R. Crozier, Elizabeth M. Curtis, Michelle Fernandes, Alexandra J. Kermack, Justin H. Davies, Keith M. Godfrey, Nicholas J. Bishop, Stephen H. Kennedy, Ann Prentice, Inez Schoenmakers, Robert Fraser, Saurabh V. Gandhi, Hazel M. Inskip, Muhammad Kassim Javaid, Aris T. Papageorghiou, Cyrus Cooper, Nicholas C. Harvey

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Background: Observational studies relating maternal 25-hydroxyvitamin D status to timing and mode of delivery have reported inconsistent results. We assessed the effect of antenatal cholecalciferol supplementation on the incidence of preterm birth, delivery mode and post-partum haemorrhage (PPH).  

Methods: MAVIDOS was a randomized, double-blind, placebo-controlled trial of 1000 IU/day cholecalciferol from 14 weeks’ gestation until delivery. Gestational age, mode of delivery [categorized as spontaneous vaginal delivery (SVD), instrumental (including forceps and vacuum extraction) or Caesarean section] and PPH (>500 ml estimated blood loss) were determined from medical records.  

Results: A total of 965 women participated in the study until delivery. Gestation at birth and incidence of preterm birth (cholecalciferol 5.7%, placebo 4.5%, P = 0.43) were similar between the two treatment groups. SVD (versus instrumental or Caesarean delivery) was more likely in women randomized to cholecalciferol [Relative Risk (RR) 1.13, 95% confidence interval (CI) 1.02,1.25] due to lower instrumental (RR 0.68, 95%CI 0.51,0.91) but similar risk of Caesarean delivery (RR 0.94, 95%CI 0.74,1.19). PPH was less common in women randomized to cholecalciferol [32.1% compared with placebo (38.1%, P = 0.054) overall], but similar when stratified by delivery mode.  

Conclusions: Antenatal cholecalciferol supplementation did not alter timing of birth or prevalence of preterm birth but demonstrated a possible effect on the likelihood of SVD.
Original languageEnglish
Article numberfdac160
Pages (from-to)738-747
Number of pages10
JournalJournal of Public Health
Issue number3
Early online date28 Dec 2022
Publication statusPublished - Sep 2023


  • 25-hydroxyvitamin D
  • Caesarean
  • cholecalciferol
  • delivery
  • labour
  • post-partum haemorrhage
  • pregnancy
  • preterm birth

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