Observational Study of Vitamin D Dynamics in Women

This observational study is looking at how pregnancy, obesity, and ancestry affect how your body uses vitamin D. Researchers are giving a small, safe dose of a special type of vitamin D3 (deuterated vitamin D3) to both pregnant and non-pregnant women. They want to understand how vitamin D is absorbed and used over a 40-day period. The goal is to learn more about vitamin D metabolism during pregnancy, especially since many women have low vitamin D levels, which can be linked to problems like premature birth. This study is for women aged 20-39, who are either White or Black, and have a specific body mass index (BMI). The study is currently unclear on its recruitment status and plans to enroll 160 participants.

Study design
This is an observational study, meaning researchers will observe participants without assigning specific treatments. It aims to enroll 160 women.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
The primary endpoints for this study are measured across a 40-day study period.

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NCT02705287

Vitamin D Dynamics in Women

Recruiting
Not specifiedAges 20–39Observational
Cornell University
~160 participants
Updated 2026-04-01 on ClinicalTrials.gov
What's tested:Vitamin D dynamics-pregnantVitamin D dynamics-nonpregnant

At a glance

Recruiting sites
1 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Impact of pregnancy on serum vitamin D absorption
Measured over Across 40 days study period
+2 more outcomes measured
Pregnancy
1 sites across 1 states
New York1
  • Kimberly O. O'Brien, PhD · PRINCIPAL_INVESTIGATOR · Cornell University
  • Eva Pressman, MD · PRINCIPAL_INVESTIGATOR · University of Rochester

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Eligibility criteria

Inclusion

Self-reported White and Black women
Age 20-39
Body mass index (BMI) 1or pre-pregnancy BMI (If currently pregnant) either 18.5-24.9 kg/m2 or greater than or equal to 30 kg/m2
Singleton pregnancy
Recruited in first trimester, second trimester, or third trimester
No pregnancy complications

Exclusion

BMI or pre-pregnancy BMI \<18.5 kg/m2
Human immunodeficiency virus (HIV) infection
Diagnosed eating disorder
Malabsorption disease
Diabetes
Elevated diastolic blood pressure (\>110 mm/Hg)
Steroid use
Substance abuse history
Current use of medications known to influence vitamin D or calcium homeostasis
Plans to travel to lower latitude during the 20-day study period
Plans to become pregnant during the study period (non-pregnant only)
Refuses to discontinue tanning bed use during study period
Refuses to discontinue vitamin or mineral supplement use during study period (non-pregnant only)
Gestational diabetes
Pregnancy hypertension
  • Impact of pregnancy on serum vitamin D absorptionAcross 40 days study period

    A baseline blood sample (20 mL) will be obtained for analysis of the baseline concentrations of indicators of vitamin D status. Each woman will be asked to ingest two pieces of toast onto which a dose of 35 μg of \[6,19,19-d3\]-vitamin D3 has been added. Women will return to the at 4 hour, 8 hour, Day 2, 10, 25, and 40 (± 2 days) for an additional blood sample (15 mL each) to assess the disappearance of the tri-deuterated D3, conversion into 25(OH)D3, and serum half-life of 25(OH)D3.

  • Impact of obesity on vitamin D absorptionAcross 40 days study period

    A baseline blood sample (20 mL) will be obtained for analysis of the baseline concentrations of indicators of vitamin D status. Each woman will be asked to ingest two pieces of toast onto which a dose of 35 μg of \[6,19,19-d3\]-vitamin D3 has been added. Women will return to the at 4 hour, 8 hour, Day 2, 10, 25, and 40 (± 2 days) for an additional blood sample (15 mL each) to assess the disappearance of the tri-deuterated D3, conversion into 25(OH)D3, and serum half-life of 25(OH)D3. Body composition measure using Bioelectrical Impedance Analysis (BIA) will be conducted on Day 0 for all participants and Day 40 for he pregnant participants to obtain information on BMI and fat mass. Adipose tissue (\<1 gram) will be extracted using needle biopsy from the upper buttock area on all participants for D content analysis.

  • Impact of ancestry on serum vitamin D absorptionAcross 40 days study period

    A baseline blood sample (20 mL) will be obtained for analysis of the baseline concentrations of calcitropic hormones and indicators of vitamin D status. Each woman will be asked to ingest one quarter piece of toast onto which a dose of 35 ug of \[6,19,19-d3\]-vitamin D3 has been added. Women will return to the at 4 hour, 8 hour, Day 1, 3, 10, 25, and 40 (± 2 days) for an additional blood sample (15 mL each) to assess the disappearance of the tri-deuterated D3, conversion into 25(OH)D3, and serum half-life of 25(OH)D3. DNA will be extracted to perform ancestry genotyping and determine vitamin D binding protein genotypes.