Effects of GLP-1 RAs on Human Lactation Outcomes

NCT07720414 | Recruiting FDA Drug

• 1 other identifier: 26-1234
• Study Type: observational
• Target: 18
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Lactation; Weight Loss

Keywords

Breastmilk production; Breastmilk composition; GLP-1; Weight Loss

Outcome Measures

Primary Outcomes (2)

• Hourly milk production rate

  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

  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.

Study Arms (1)

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

Interventions

Injected GLP-1 Receptor Agonists and Dual Agonists DRUG

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.

Breastfeeding mothers prescribed GLP-1 RA therapies

Eligibility Criteria

• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

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

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• University of Colorado, Denver: lead

Study Sites (1)

University of Colorado Anschutz School of Medicine

Aurora, Colorado, 80045, United States

RECRUITING

Biospecimen

Retention: SAMPLES WITH DNA

Breastmilk samples, including milk fat globules and milk-derived cells

MeSH Terms

Conditions

Breast Feeding; Weight Loss

Condition Hierarchy (Ancestors)

Feeding Behavior; Behavior; Body Weight Changes; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Jayne F Martin Carli, PhD

CONTACT

303-724-3981; jayne.martincarli@cuanschutz.edu

Jacinda M Nicklas, MD, MPH

CONTACT

303-724-9028; jacinda.nicklas@cuanschutz.edu

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: July 17, 2026
• First Posted: July 22, 2026
• Study Start: July 1, 2026
• Primary Completion (Estimated): June 1, 2028
• Study Completion (Estimated): June 1, 2028
• Last Updated: July 22, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will share
• 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.
• 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.

Locations

US (1)