An observational study in Lactation and Weight Loss, sponsored by University of Colorado, Denver. Recruiting at 1 site in United States. Open to female participants, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-07-22.
Sponsored by University of Colorado, Denver · Observational
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:
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:
During each visit, participants will:
Breastfeeding mothers willing to attend study study visits in Aurora, CO.
Exclusion Criteria:
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.
Hourly milk production rate
Milk production rate (in grams per hour) will be assessed using a standardized milk expression protocol.
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 macronutrient composition
Milk macronutrient composition will be assessed using the Miris Human Milk Analyzer.
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.
Plan to share: Yes — 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.
No publications or documents are linked to this record.
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University of Colorado, Denver