Effects of GLP-1 RAs on Human Lactation Outcomes

July 17, 2026 updated by: University of Colorado, Denver

There is increasing interest in using GLP-1 Receptor Agonist (GLP-1 RA) medications after pregnancy. This study is designed to determine if these medications affect breastmilk production or the nutritional makeup of breastmilk.

The main questions the study will address are:

  • Does GLP-1 RA-induced weight loss increase or decrease breastmilk production?
  • Does GLP-1 RA-induced weight loss affect the nutritional composition of milk, including milk fat content?

Researchers will assess milk production rates before and after mothers begin taking injected GLP-1 RA medications to decrease their body weight. Weight loss will be confirmed with 7-day body weight averages.

Participants will:

  • Weigh themselves and report measurements daily.
  • Participate in 2-3 morning study visits over approx. 2.5-4.5 months (approx. 3-3.5hrs each).

During each visit, participants will:

  • Use a study provided breastpump to express milk 3 times hourly for measurement of hourly milk production.
  • Provide 1-3 oz of milk for further study.
  • Answer questions about breastfeeding patterns.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
18

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

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • Colorado
      • Aurora, Colorado, United States, 80045
        • Recruiting
        • University of Colorado Anschutz School of Medicine

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

Breastfeeding mothers willing to attend study study visits in Aurora, CO.

Description

Inclusion Criteria:

  • Breastfeeding mothers of single or multiple infants.
  • Milk removal at least 4x daily
  • Eligible for a GLP-1 RA administered subcutaneously (oral GLP-1 RAs contain absorption enhancers, which may drive accumulation in milk)
  • Access to a breastpump, if needed for maintaining breastfeeding behaviors.
  • Willingness to provide 1-3 oz of breastmilk per study visit.
  • Willingness to track and report body weight daily.
  • Willingness to maintain breastfeeding behaviors for the duration of the study.

Exclusion Criteria:

  • Currently taking GLP-1 RA medication or other weight loss medication
  • Induced lactation, due to unknowns regarding the durability of the mammary gland's milk production after exogenous stimulation.

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

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Breastfeeding mothers prescribed GLP-1 RA therapies
Breastfeeding mothers who have been prescribed, but have not started, an injected GLP-1RA (these patients have an indication for GLP-1 RA treatment (BMI ≥27 kg/m2 with at least one comorbidity (prediabetes, diabetes, metabolic syndrome, obstructive sleep apnea, hypertension, dyslipidemia, cardiovascular disease, heart failure, chronic kidney disease, metabolic dysfunction-associated steatohepatitis, atrial fibrillation, venous thromboembolic disease, osteoarthritis, polyendocrine metabolic ovarian syndrome), or BMI ≥30 kg/m2)) and who are committed to sustaining breastfeeding habits (frequency and volume of milk removal) for the duration of the study period.
Drug: Injected GLP-1 Receptor Agonists and Dual Agonists
Participants are prescribed this medication by their care provider(s) as part of their postnatal clinical care, including but not limited to semaglutide and tirzepatide. The investigators do not provide, manage, or assign the medication.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Hourly milk production rate
Time Frame: From one week before until a maximum of 2 months after beginning GLP-1RA treatment. This timeframe will restart if their dosage is increased.
Milk production rate (in grams per hour) will be assessed using a standardized milk expression protocol.
From one week before until a maximum of 2 months after beginning GLP-1RA treatment. This timeframe will restart if their dosage is increased.
Milk macronutrient composition
Time Frame: From one week before until a maximum of 2 months after beginning GLP-1RA treatment. This timeframe will restart if the dosage is increased.
Milk macronutrient composition will be assessed using the Miris Human Milk Analyzer.
From one week before until a maximum of 2 months after beginning GLP-1RA treatment. This timeframe will restart if the dosage is increased.

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of Colorado, Denver

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 (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
July 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
June 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
July 17, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 17, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
July 22, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 22, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 17, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 26-1234

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data and leftover biological samples may be deposited into public or restricted-access data banks, or distributed directly to external researchers for future study without additional participant consent. Data and specimens will be stripped of names and direct identifiers prior to sharing or repository submission. Recipients of these assets may include researchers working at other universities, government agencies, or private industry. Future research utilizing this data may focus on obesity, weight loss treatments, or other related medical conditions. While data are de-identified to protect privacy, absolute protection against re-identification cannot be guaranteed, and broad data sharing may involve unknown risks.

IPD Sharing Time Frame

Data will be made available following the primary completion of the study and publication of main results, or upon deposition into designated data repositories.

IPD Sharing Access Criteria

Data and leftover samples will be accessible to qualified researchers across academic, government, and private industry sectors. Access to data housed in restricted data banks will be governed by the specific repository's data access committee. Direct requests to the study investigators will require a scientifically valid proposal.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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.

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Dietary Supplements

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