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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Does Vitamin D supplementation in pregnancy improve maternal glucose metabolism or prevent gestational diabetes?
Scientific title
Effect of high-dose versus low-dose vitamin D supplementation in pregnancy on maternal glucose metabolism and the risk of gestational diabetes.
Secondary ID [1] 281424 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Gestational Diabetes 237276 0
Pregnancy 287675 0
Condition category
Condition code
Metabolic and Endocrine 239599 239599 0 0
Normal metabolism and endocrine development and function
Reproductive Health and Childbirth 288058 288058 0 0
Antenatal care

Study type
Description of intervention(s) / exposure
Pregnant women will be randomly allocated to take high-dose vitamin D supplementation (5000IU/day) or standard dose pregnancy vitamin supplementation (400 IU vitamin D daily), administered as an oral capsule, from the time of the first antenatal clinic visit (around 12 weeks gestation) until delivery.
Intervention code [1] 236959 0
Treatment: Drugs
Intervention code [2] 285966 0
Comparator / control treatment
Standard dose vitamin D supplementation (as in commonly used pregnancy multivitamin preparations)
Control group
Dose comparison

Primary outcome [1] 238392 0
Maternal glucose metabolism in late second trimester (26-28 weeks gestation) assessed by glucose tolerance test (blood analysis after ingestion of 75g oral glucose).
Timepoint [1] 238392 0
26-28 weeks gestation
Primary outcome [2] 238393 0
Diagnosis of Gestational Diabetes, determined by an oral Glucose Tolerance Test (blood analysis after ingestion of 75g oral glucose) performed at 26-28 weeks gestation, or other evidence of hyperglycaemia recorded throughout pregnancy.
Timepoint [2] 238393 0
End of pregnancy
Secondary outcome [1] 244854 0
Infant weight at birth, infant length (assessed with a newborn stadiometer) and head circumference.
Timepoint [1] 244854 0
First week of life

Key inclusion criteria
Pregnancy, less than 20 weeks gestation at recruitment.
Minimum age
18 Years
Maximum age
No limit
Can healthy volunteers participate?
Key exclusion criteria
Known diabetes
Calcium metabolic disorder
Multiple pregnancy

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Patients will be recruited at their first antenatal clinic visit. Baseline tests will exclude pre-existing diabetes, hypercalcaemia or vitamin D toxicity. Treatment will be stratified according to baseline serum vitamin D levels and randomized by the trial pharmecist using opaque envelopes containing a treatment allocation. Patient, treating clinician and researchers will remain blinded to treatment group.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Opaque envelopes containing treatment allocation to one of 2 dose levels of Vitamin D (identical capsules). Permuted block randomisation.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Phase 4
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Active, not recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment postcode(s) [1] 1940 0

Funding & Sponsors
Funding source category [1] 237344 0
Name [1] 237344 0
Westmead Hospital
Address [1] 237344 0
Hawkesbury Road
Westmead NSW 2145
Country [1] 237344 0
Primary sponsor type
Westmead Hospital
Hawkesbury Road
Westmead NSW 2145
Secondary sponsor category [1] 236835 0
Name [1] 236835 0
University of Western Sydney
Address [1] 236835 0
University of Western Sydney
Locked Bag 1797
Penrith South DC
NSW 2751
Country [1] 236835 0

Ethics approval
Ethics application status
Ethics committee name [1] 239464 0
Western Sydney Local Health District Human Research Ethics Committee
Ethics committee address [1] 239464 0
Westmead Hospital
Hawkesbury Road
Westmead NSW 2145
Ethics committee country [1] 239464 0
Date submitted for ethics approval [1] 239464 0
Approval date [1] 239464 0
Ethics approval number [1] 239464 0
AU RED HREC/09/WMEAD/54 HREC2009/4/4.1 (2953)

Brief summary
This study will determine whether taking additional Vitamin D supplementation in pregnancy, above that contained in conventional pregnancy vitamin tablets, improves a woman's glucose metabolism and prevents the development of gestational diabetes, a common complication of pregnancy in Australia.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 29915 0
Address 29915 0
Country 29915 0
Phone 29915 0
Fax 29915 0
Email 29915 0
Contact person for public queries
Name 13162 0
Mark McLean
Address 13162 0
Professor Mark McLean
University of Western Sydney - Blacktown Clinical School
Blacktown Hospital
PO Box 6105 BLACKTOWN NSW 2148
Country 13162 0
Phone 13162 0
+61 2 9851 6073
Fax 13162 0
+61 2 9851 6050
Email 13162 0
Contact person for scientific queries
Name 4090 0
Mark McLean
Address 4090 0
Professor Mark McLean
University of Western Sydney - Blacktown Clinical School
Blacktown Hospital
PO Box 6105 BLACKTOWN NSW 2148
Country 4090 0
Phone 4090 0
+61 2 9851 6073
Fax 4090 0
+61 2 9851 6050
Email 4090 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary