Effects of Vitamin D Supplementation During Pregnancy on Clinical Outcomes and Immune Function

Assessment of Inflammatory Markers and Pregnancy Outcomes in Vitamin D-Supplemented Women at Risk of Vitamin D Deficiency: A Double-Blind, Randomized Controlled Trial

Status

Completed

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT01417351

Enrollment

Registered

2011-08-16

Start date

2010-08-31

Completion date

2013-05-31

Last updated

2013-07-23

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Vitamin D Deficiency

Keywords

pregnancy, immune function

Brief summary

Researchers at the USDA Western Human Nutrition Research Center and clinicians at UC Davis Medical Center are currently conducting a study on the effects of vitamin D supplementation during pregnancy on maternal health and immune function. The investigators believe that vitamin D supplementation at levels greater than the current recommendation is beneficial for maternal health during pregnancy. In particular, there is evidence that vitamin D deficiency during pregnancy puts women at greater risk for diseases like pre-eclampsia, which may be due to an imbalance in immune function at the placenta. This randomized, double-blind study is designed to test this hypothesis. Pregnant women who participate in the study receive either 400 IU or 2,000 IU of vitamin D per day for the duration of their pregnancy. The investigators will collect blood at three time points during pregnancy (16-20 weeks, 26-28 weeks, 36 weeks gestation) for analysis of immune function and vitamin D status. The investigators are also collecting data on clinical parameters, such as blood pressure and glucose tolerance.

Interventions

DIETARY_SUPPLEMENT400 IU vitamin D3

Women in this study arm receive 400 IU of vitamin D3 per day, or what is in a standard prenatal multivitamin. They also receive a placebo study supplement.

DIETARY_SUPPLEMENT2,000 IU Vitamin D3

Women in this arm receive 2,000 IU vitamin D per day: 400 IU from a standard prenatal multivitamin plus an additional 1,600 IU vitamin D3 in the study supplement.

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

BASIC_SCIENCE

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

FEMALE

Age

18 Years to 45 Years

Healthy volunteers

Yes

Inclusion criteria

* Pregnant women * Less than 20 weeks gestation * Over 18 years of age * Able to swallow nutritional supplements

Exclusion criteria

* Use of medications known to affect vitamin D metabolism * Diagnosis of type 1 diabetes * History of thyroid, renal, or liver disease * Problems with digestion or absorption

Design outcomes

Primary

Measure	Time frame	Description
Change in T-cell cytokine expression	16-20 wks, 26-28 wks, and 36 wks gestation	Inflammatory and regulatory cytokines will be measured in cultured T-cells by flow cytometry.

Secondary

Measure	Time frame	Description
Change in Vitamin D status	16-20 wks, 26-28 wks, 36 wks gestation	Serum 25-OH vitamin D and 1, 25 (OH)2 Vitamin D
Change in innate immune function	16-20 wks, 26-28 wks, 36 wks gestation	Monocyte and NK cell cytokine expression and response to stimulation with Toll-like Receptor agonists.
Change in blood pressure	16-20 wks, 26-28 wks, 36 wks gestation	Blood pressure will be measured using standard techniques.

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Mar 12, 2026