Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT04764955 |
| Other study ID # |
1000061108 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
Phase 3
|
| First received |
|
| Last updated |
|
| Start date |
March 2014 |
| Est. completion date |
March 2018 |
Study information
| Verified date |
June 2023 |
| Source |
The Hospital for Sick Children |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
This is a secondary-use study based on previously-collected data and blood samples from a
previously completed double-blind, dose-ranging trial of maternal prenatal and postpartum
vitamin D supplementation in Dhaka, Bangladesh (NCT01924013). The aim of this sub-study is to
examine the effect of vitamin D supplementation on iron status during pregnancy and early
infancy.
Description:
The risk of both low iron and vitamin D status have been recognized as public health concerns
among pregnant women and young children, with high rates of deficiency in low-and
middle-income countries. Through its involvement in regulation of the hepcidin-ferroportin
axis, as well as its potential to increase the expression of the erythropoietin receptor,
vitamin D has been suggested as a modulator of iron homeostasis. Vitamin D supplementation
may therefore represent a candidate facilitator for the management of iron deficiency, yet
few intervention trials have directly assessed the effect of vitamin D supplementation on
biomarkers of iron status.
To examine the effect of vitamin D supplementation on iron status during pregnancy and early
infancy, data and blood samples will be drawn from a completed double-blind, dose-ranging
trial of maternal prenatal and postpartum vitamin D supplementation. Women at 17-24 weeks'
gestation were randomized to 1 of 5 dose groups comprising a prenatal; postpartum regimen of
placebo; placebo, 4200;0, 16800;0, 28000;0 or 28000;28000 IU vitamin D3/week until 26 weeks
postpartum. Enrolment (n=1300) was completed in September 2015, and all infants were
delivered by February 2016. The MDIG trial was primarily designed to determine the effect of
maternal vitamin D on infant length at 12 months of age (with follow-up continuing until
infants reached 24 months of age; completed in March 2018).
Analyses of serum ferritin and related iron biomarkers (serum iron, transferrin, soluble
transferrin receptor, hepcidin), and inflammatory makers (e.g. CRP), will be conducted using
previously collected stored blood samples. Linear regression models will be used to assess
the effect of vitamin D supplementation on the biomarkers of interest among pregnant women
and their infants at 6 months of age.
To examine the potential dose-response relation between prenatal vitamin D treatment dose
(i.e., across all 4 assigned prenatal vitamin D doses by combining the 2 high-dose prenatal
vitamin D treatment groups) and the biomarker of interest, linear regression models will be
fitted using the assigned prenatal vitamin D treatment group as the categorical exposure
variable and the specified biomarker as the (continuous) outcome variable. Data will be
reported as mean differences (or mean % differences, if applicable) and 95% CIs.
To explore potential effects of prenatal only versus prenatal plus postpartum vitamin D
supplementation on Hb and ferritin concentrations among infants at 6 months of age, a similar
dose-response analysis will be conducted across all 5 treatment groups (i.e., disaggregation
of the 2 high-dose prenatal vitamin D groups), for which the investigators will regress the
biomarker (Hb as a continuous variable) on the vitamin D treatment group assigned during the
prenatal and postpartum periods (as a categorical variable). Differences in each
supplementation group will therefore be compared to the placebo group, and expressed as mean
differences (or geometric means, or mean % differences, if applicable) and 95% CIs.
Given the influence of inflammation on serum ferritin concentrations, secondary analyses will
include inflammatory markers (e.g. CRP) as covariates to test the role of inflammation in
mediating the association between the vitamin D intervention and serum ferritin
concentrations.
