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Effects of GLP-1 RAs on Human Lactation Outcomes

Who can join

All ages · Women · Healthy volunteers welcome

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.

About the study

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.

What is being tested

• Injected GLP-1 Receptor Agonists and Dual Agonists (drug)

Sponsor: University of Colorado, Denver · Participants: 18 · Started: 2026-07

Contact the study team

• Jayne F Martin Carli, PhD · Phone: 303-724-3981
• Jacinda M Nicklas, MD, MPH · Phone: 303-724-9028

Official record on ClinicalTrials.gov — NCT07720414

Locations in the U.S.

Conditions

• Breastfeeding
• Weight Control

From ClinicalTrials.gov, data retrieved Sep 30, 2026. Each study sets its own eligibility; the study team decides who can join.