Calcium Plus Vitamin D Supplementation Affects Pregnancy Outcomes in Gestational Diabetes: Randomized, Double-Blind, Placebo-Controlled Trial

Public Health Nutr. 2016 Jan;19(1):156-63. doi: 10.1017/S1368980015000609. Epub 2015 Mar 20.


Objective: The present study was designed to assess the effects of Ca+vitamin D supplementation on pregnancy outcomes in women with gestational diabetes mellitus (GDM).

Design: A randomized, double-blind, placebo-controlled trial was conducted among sixty women with GDM. Participants were divided into two groups to receive Ca+vitamin D supplements or placebo. Individuals in the Ca+vitamin D group (n 30) received 1000 mg Ca/d and two pearls containing 1250 µg (50 000 IU) of cholecalciferol (vitamin D(3)) during the intervention (one at study baseline and another at day 21 of the intervention); those in the placebo group (n 30) received two placebos of vitamin D at the mentioned times and placebos of Ca every day for 6 weeks. Pregnancy outcomes were determined.

Setting: A urban community setting in Arak, Iran.

Subjects: Sixty women with GDM and their newborns, living in Arak, Iran were enrolled.

Results: Women treated with Ca+vitamin D had a significant decrease in caesarean section rate (23·3 % v. 63·3 %, P=0·002) and maternal hospitalization (0 v. 13·3 %, P=0·03) compared with those receiving placebo. In addition, newborns of GDM women randomized to Ca+vitamin D had no case of macrosomia, while the prevalence of macrosomia among those randomized to placebo was 13·3 % (P=0·03). Lower rates of hyperbilirubinaemia (20·0 % v. 56·7 %, P=0·03) and hospitalization (20·0 % v. 56·7 %, P=0·03) were also seen in the supplemented group of newborns than in the placebo group.

Conclusions: Ca+vitamin D supplementation for 6 weeks among pregnant women with GDM led to decreased caesarean section rate and maternal hospitalization, and decreased macrosomia, hyperbilirubinaemia and hospitalization in newborns.

Keywords: Calcium; Gestational diabetes mellitus; Pregnancy outcomes; Supplementation; Vitamin D.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Blood Glucose / metabolism
  • Body Mass Index
  • Body Weight
  • Calcium, Dietary / administration & dosage*
  • Calcium, Dietary / blood
  • Cesarean Section
  • Cholecalciferol / administration & dosage
  • Cholecalciferol / blood
  • Diabetes, Gestational / blood
  • Diabetes, Gestational / drug therapy*
  • Dietary Supplements*
  • Double-Blind Method
  • Female
  • Fetal Macrosomia / blood
  • Fetal Macrosomia / prevention & control
  • Follow-Up Studies
  • Hospitalization
  • Humans
  • Hyperbilirubinemia / blood
  • Hyperbilirubinemia / prevention & control
  • Iran
  • Pregnancy
  • Pregnancy Complications / blood
  • Pregnancy Complications / prevention & control
  • Pregnancy Outcome*
  • Vitamin D / administration & dosage*
  • Vitamin D / blood
  • Young Adult


  • Blood Glucose
  • Calcium, Dietary
  • Vitamin D
  • Cholecalciferol