Storing Human Milk

Do you need to express and store your own milk for later use? Storing your milk according to current recommendations will help maintain its safety and quality. Following the recommendations can minimize the loss of antibodies, nutrients and antioxidant qualities while in storage. Before expressing or pumping milkMilk Storage GuidelinesGeneral storage tipsStorage ContainersReheating Human MilkCommon QuestionsAdditional ResourcesReferences This information is based on current recommendations and applies to those who have healthy, full-term babies. Families with babies who are preterm, in neonatal intensive care unit (NICU), or ill may be advised by their health team to use stricter guidelines. Storage guidelines may differ slightly between organizations. Below are two versions. Academy of Breastfeeding Medicine (ABM)Human Milk Storage Guidelines for Full-Term Infants United States Centers for Disease Control (CDC)Human Milk Storage Guidelines for Full-Term Infants While many infants may be content drinking room temperature milk, some may have a preference for warmer milk. Experts recommend to warm milk slowly in lukewarm water to protect the fat content and nutrients. There are several safe ways to thaw frozen milk: Avoid boiling and do not microwave human milk. These methods will cause loss of nutritional properties of the milk. Microwaving can heat the milk unevenly, producing hot spots that could cause burns.  (ABM, 2017). Expressed human milk may undergo odor changes when stored. Parents sometimes describe expressed or defrosted milk as smelling odd — metallic, soapy, or even rancid. The reasons are not well understood, but it may be due to the breakdown of milk fats over time. If stored properly, this milk is safe and most babies will drink it. For more information see: Milk issues – Smell of Stored Human Milk. Human milk naturally separates into a milk layer and an upper cream layer when it is stored. This is normal. Shake or swirl the milk to combine the cream prior to feeding. Previously-frozen milk that has been thawed can be kept in the refrigerator for up to 24 hours (Lawrence & Lawrence, 2010). There is  little research on the safety of refreezing human milk, but it may introduce further breakdown of nutrients and increase the risk of bacterial growth. At this time, the accepted practice is not to refreeze thawed milk. The Academy of Breastfeeding Medicine Human Milk Storage protocol (2017) states that there have not been many studies examining this. The ABM suggests that human milk stored in a small cooler with an ice pack could be safe for up to 24 hours. Aim to transfer your milk to a refrigerator or freezer for reliable storage temperatures as soon as possible.If a cooler with ice pack is not available, researchers have suggested that the container with expressed milk can be immersed/surrounded by a vessel with cold water.The findings from an Nigerian study suggested that storage of breast milk either at room temperature or immersed in a container of water appeared to be safe for up to 9 hours of storage in a tropical environment. (Ukegbu, PO et al,2013) If your baby does not finish the bottle during a feed, experts recommend using the remaining milk within two hours. Discard any milk left after this time frame. (ABM, 2017). Storing milk in smaller quantities can help reduce waste if your baby does not finish the bottle. Milk kept beyond the recommended storage guidelines may be used for external use. Some parents use it for skin baths or even making soap. However, there is no guidance or research on these practices. The storage guidelines for all types of  freezers are the same. The Center for Disease Control states that storage guidelines depend on the temperature of the freezer, not the type of freezer. Storage guidelines specify freezing at temperatures of 0° F (-17.8° C) or less. If your refrigerator freezer meets these temperatures, then the guideline applies.  More information here. Expressed milk can be kept in a common refrigerator at the workplace or in a day care center. The US Centers for Disease Control and the US Occupational Safety and Health Administration agree that human milk is not among the body fluids that require special handling or storage in a separate container (CDC, 2023). According to the Academy of Breastfeeding Medicine and several other sources, there is no need to discard milk that was pumped during a mother’s presumed thrush infection. For more details and references see the our article on thrush. If your baby has thrush in their mouth, research suggests that thrush is not automatically passed along to you through breastfeeding. Therefore, continued breastfeeding is not a concern. Experts recommend that you feed human milk separately from any formula to maximize the benefits of human milk. For more details see this article. Human milk stored in the refrigerator or freezer continues to provide excellent nutrition and other health support. Offering the freshest milk available may have health advantages. Consider how much milk you need in storage. This will vary depending on your own circumstances. While it can be reassuring to have some amount as backup, consider making just what your baby needs in your situation. Many mothers who are separated from their children after returning to work or school express and leave milk for the next day. They may have a small freezer backup or stash for emergencies only.  See this article. LLL Canada, Storing Human Milk LLL USA, Storing Human Milk Nancy Mohrbacher, Why Do Milk Storage Guidelines Differ? Academy of Breastfeeding Medicine. (2017) Clinical Protocol Number #8: Human Milk Storage Information for Home Use for Healthy Full Term Infants.  Breastfeeding Medicine, 12(7), 390-395. Centers for Disease Control and Prevention (CDC). (2023). Breast Milk Storage and Preparation Retrieved from https://www.cdc.gov/breastfeeding/breast-milk-preparation-and-storage/handling-breastmilk.html Centers for Disease Control and Prevention (CDC). (2023). Breast Milk Storage Questions and Answers Retrieved from https://www.cdc.gov/breastfeeding/php/guidelines-recommendations/faqs.html Jimenez et al. Mammary candidiasis: A medical condition without scientific evidence? PLoS ONE, 12(7): e0181071, 2017, https://eadn-wc01-5994650.nxedge.io/wp-content/uploads/2021/08/JimenezetalCandidiasnotcauseofpain.pdf Lawrence, R.A. & Lawrence, R.M. (2010). Breastfeeding: A Guide for the Medical Profession (7th ed.). Elsevier Mosby, Philadelphia Morbacher, Nancy (2020). Breastfeeding Answers (2nd ed.). Arlington Heights, IL: Nancy Morbacher Solutions, Inc., 726-31. Newman, J. & Pitman, T. (2014). Dr. Jack Newman’s Guide to Breastfeeding, Revised Edition. UK: Pinter & Martin, Ltd. Ukegbu, PO et al,(2013)  Bacterial Load in Expressed and Stored Breast Milk of Lactating Mothers in Abia State, Nigeria, African Journal of Food, Agriculture, Nutrition and Development (ajol.info) Published 2018, revised July 2024