Effects of GLP-1 RAs on Human Lactation Outcomes

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.