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

• Published in: The American journal of clinical nutrition Vol. 114; no. 3; pp. 1208 - 1218
• Main Authors: Alhomaid, Raghad M, Mulhern, Maria S, Strain, JJ, Laird, Eamon, Healy, Martin, Parker, Michael J, McCann, Mary T
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2021; American Society for Clinical Nutrition, Inc; Oxford University Press
• Subjects: 25(OH)D concentration; 25-Hydroxyvitamin D; Adult; BMI; body weight; Calciferol; Dietary Supplements; Dose-Response Relationship, Drug; Double-Blind Method; Double-blind studies; Female; Fetal Blood; Humans; Infant, Newborn; maternal obesity; Obesity; Obesity, Maternal; Original Research Communications; Pregnancy; Supplements; Umbilical cord; Vitamin D; Vitamin D - administration & dosage; Vitamin D - blood; Vitamin D Deficiency - drug therapy; vitamin D requirements; Vitamin D3; maternal obesity; vitamin D; pregnancy; DRV; iPTH; body weight; GW; LC-MS/MS; 25(OH)D concentration; WHSCT; 25(OH)D; BMI; vitamin D requirements
• ISSN: 0002-9165; 1938-3207; 1938-3207
• DOI: 10.1093/ajcn/nqab112

The achievement of target 25-hydroxyvitamin D [25(OH)D] concentrations in pregnancy may be altered by maternal obesity. The authors examined the effects of maternal supplementation of 10 μg compared with 20 μg vitamin D3/d on maternal and umbilical cord 25(OH)D. The secondary aim was to investigate the influence of maternal BMI (in kg/m2) on the response of the primary outcomes. The authors performed a 2-arm parallel double-blind randomized trial with 240 pregnant women recruited throughout the year in Northern Ireland. Women were stratified by BMI to receive 10 or 20 µg vitamin D3/d from 12 gestational wk (GW) until delivery. Maternal blood samples collected at 12, 28, and 36 GW and from the umbilical cord were analyzed for total serum 25(OH)D. A total of 166 women completed the study. Mean ± SD 25(OH)D at 36 GW was 80.8 ± 28.2 compared with 94.4 ± 33.2 nmol/L (P < 0.001) (10 compared with 20 µg vitamin D3/d, respectively). In those classified with 25(OH)D <50 nmol/L at baseline and assigned 10 µg vitamin D3/d, mean 25(OH)D concentrations remained <50 nmol/L at 36 GW, whereas those <50 nmol/L at baseline and assigned 20 µg vitamin D3/d, had mean 25(OH)D concentrations ≥50 nmol/L at 28 and 36 GW. In women with obesity and 25(OH)D <50 nmol/L at baseline, the related mean umbilical cord 25(OH)D was deficient (<25 nmol/L) in both treatment groups, whereas those with obesity and 25(OH)D ≥50 nmol/L at baseline had an average umbilical cord 25(OH)D between 25 and 50 nmol/L in both treatment groups. Supplementation of 20 µg 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 concentrations (<50 nmol/L). Under current recommendations, women with obesity and low 25(OH)D in early pregnancy are particularly vulnerable to maintaining a low 25(OH)D concentration throughout pregnancy and having an infant born with deficient 25(OH)D concentrations. This trial was registered at ClinicalTrials.gov as NCT02713009.