Maternal obesity and baseline vitamin D insufficiency alter the response to vitamin D supplementation: a double blind, randomized trial in pregnant women: Maternal and fetal vitamin D requirements

Raghad Alhomaid, Maria S Mulhern, JJ Strain, Eamon Laird, Martin Healy, Michael J. Parker, M McCann

Research output: Contribution to journalArticlepeer-review

Abstract

Background: The achievement of target 25-hydroxyvitamin D (25(OH)D) concentrations in pregnancy may be altered by maternal obesity. Objective: To compare maternal supplementation of 10μg vs 20μg vitamin D3/d on maternal and umbilical cord 25(OH)D. The secondary aim was to investigate the influence of maternal BMI on the response of the primary outcomes. Design: A two-arm parallel double-blind randomized trial with 240 pregnant women, recruited throughout the year in Northern Ireland. Women were stratified by BMI to receive 10µg or 20µg vitamin D3/d from 12 gestational weeks (GW) until delivery. Maternal blood samples collected at 12, 28 and 36 GW and from umbilical cord were analyzed for total serum 25(OH)D. A total of 166 women completed the study.Results: Mean ± SD 25(OH)D at 36 GW was 80.8 ± 28.2 vs. 94.4 ± 33.2 nmol/L, (P<0.001) (10µg vs. 20µg vitamin D3/d respectively). In those classified with 25(OH)D <50nmol/L at baseline and assigned 10µg vitamin D3/d, mean 25(OH)D concentrations remained <50nmol/L at 36 GW, whilst those <50nmol/L at baseline and assigned 20µg vitamin D3/d, had mean 25(OH)D concentrations ≥50nmol/L at 28 and 36GW. In women with obesity and 25(OH)D <50nmol/L at baseline, the related mean umbilical cord 25(OH)D was deficient (<25nmol/L) in both treatment groups, whereas those with obesity and 25(OH)D ≥50nmol/L at baseline, had average umbilical cord 25(OH)D between 25-50 nmol/L in both treatment groups.Conclusions: Supplementation of 20µg vitamin D3/d is needed to attain maternal and umbilical cord 25(OH)D concentrations ≥50 nmol/L on average, in those who start pregnancy with low 25(OH)D (<50nmol/L). Under current recommendations, women with obesity and low 25(OH)D in early pregnancy, are particularly vulnerable to a maintaining a low 25(OH)D throughout pregnancy and having an infant born with deficient 25(OH)D concentrations.
Original languageEnglish
Article numbernqab112
JournalThe American Journal of Clinical Nutrition
Early online date8 May 2021
DOIs
Publication statusE-pub ahead of print - 8 May 2021

Keywords

  • Maternal obesity
  • Body weight
  • BMI
  • Pregnancy
  • 25(OH)D concentration
  • vitamin D
  • vitamin D requirements

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