Beyond MARS: Magnetic Resonance Study: A Novel Assessment of Placental Perfusion During Pregnancy

March 13, 2026 updated by: Caitlin MacGregor, Endeavor Health

The purpose of this study is to evaluate the flow of oxygen and blood necessary for nutrient transfer across the placenta during the second and third trimesters in pregnancy in women who are obese before pregnancy compared to women who have an average weight before pregnancy.

This study will evaluate blood flow across the placenta by functional Magnetic Resonance Imaging (fMRI). The investigators hypothesize that there will be differences in placental oxygenation and blood flow among women with obesity as compared to those with normal weight.

Participants will be asked to complete:

  • MRI in the second trimester (20-24 weeks)
  • MRI in the third trimester (30-34 weeks)

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The transfer of oxygen and nutrients from the mother to the baby across the placenta is essential to successful pregnancy outcomes. Conversely, poor transfer of oxygen from the mother to the baby through the placenta is associated with adverse outcomes, including poor fetal growth, preterm delivery, and stillbirth. Babies need oxygen to maintain good health. Babies born to women who are obese before pregnancy have a higher risk of experiencing health problems in pregnancy and long-term health problems such as metabolic syndrome, obesity, and diabetes. Obesity has continued to increase in the United States over the past decades, and a quarter of pregnancy complications, such as preterm birth, gestational diabetes, hypertension, and large gestational infants, can be attributed to maternal obesity.

In this study, the investigators propose using a novel method, arterial spin labeling (ASL)) to measure placental blood flow. The study aims to evaluate the feasibility and reliability of assessing placental blood flow by this novel method. The investigators will also evaluate the mean global placental perfusion of second and third trimester placentas among obese women as compared to those with a normal weight before pregnancy. To provide an innovative and comprehensive evaluation of placental oxygen delivery and insights into the delivery of nutrients, investigators will compare global placental perfusion of second and third trimester placentas with measurements of placental oxygenation by R2* relaxation rates.

Study Type

Observational

Enrollment (Estimated)

30

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Pregnant people at 20-24 weeks gestation. 15 obese (OB) women and 15 normal weight (NW) will be recruited to participate in the study.

OB is defined as pre-pregnancy body mass index greater than or equal to 30 kg/m2, and NW is defined as pre-pregnancy body mass index between 18.5-24.9 kg/m2 without comorbidities.

Description

Inclusion Criteria:

  • Singleton pregnancy, less than 24 weeks gestation
  • Pre-pregnancy BMI between 18.5 - 24.9kg/m2 or ≥30kg/m2

Exclusion Criteria:

  • Asthma on controller medication
  • Autoimmune Conditions
  • Chronic Hypertension
  • Claustrophobia
  • Congenital Anomaly
  • Pregestational Diabetes
  • History of Bariatric Surgery
  • HIV
  • Ineligible for MRI (incompatible implanted medical device)
  • Multifetal Gestation
  • Smoking during pregnancy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Normal Weight
Body Mass Index (BMI) 18.5-24.9 kg/m^2
Diagnostic test: functional Magnetic Resonance Imaging (fMRI)
Participants will undergo a functional Magnetic Resonance Imaging (fMRI) using arterial spin labeling (ASL) and other Magnetic Resonance (MR) sequences
Obese
Pre-pregnancy Body Mass Index (BMI) ≥ 30.0 kg/m^2
Diagnostic test: functional Magnetic Resonance Imaging (fMRI)
Participants will undergo a functional Magnetic Resonance Imaging (fMRI) using arterial spin labeling (ASL) and other Magnetic Resonance (MR) sequences

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Inter - rater reliability of assessing placental blood flow by arterial spin labeling (ASL)
Time Frame: 6 weeks after the delivery
Evaluated using a two-way mixed intraclass correlation coefficient for consistency
6 weeks after the delivery
Mean placental perfusion in second and third trimester
Time Frame: 6 weeks after the delivery
The mean global placental perfusion of second and third-trimester placentas among participants with obesity (Body Mass Index measured in kg/m^2, calculated using weight in kilograms and height in meters) as compared to those with a normal weight (kilograms) before pregnancy will be evaluated.
6 weeks after the delivery
Mean R2* relaxation rates in second and third trimester
Time Frame: 6 weeks after the delivery
the Mean R2* relaxation rates will be used to correlate the global placental perfusion of second and third trimester placentas with measurements of placental oxygenation.
6 weeks after the delivery

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Perinatal outcomes including hypertensive disorders of pregnancy, gestational diabetes, preterm birth, small for gestational age, NICU admission, and stillbirth.
Time Frame: 6 weeks after the delivery
The prevalence and incidence of outcomes such as hypertensive disorders of pregnancy, gestational diabetes, preterm birth, small for gestational age, NICU (Neonatal Intensive Care Unit) admission, stillbirth will be assessed.
6 weeks after the delivery

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Endeavor Health

Investigators

  • Principal Investigator: Caitlin MacGregor, Endeavor Health

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 9, 2024

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

February 16, 2024

First Submitted That Met QC Criteria

March 13, 2024

First Posted (Actual)

March 15, 2024

Study Record Updates

Last Update Posted (Actual)

March 16, 2026

Last Update Submitted That Met QC Criteria

March 13, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • EH23-302

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Pregnancy

Clinical Trials on functional Magnetic Resonance Imaging (fMRI)

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Peru

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe