Updated Guidelines for Breastmilk Storage

The following information is taken from the 2017 revised guidelines for storage of breastmilk for fullterm infants by the American Academy of Breastfeeding Medicine.

Human milk is a fresh, living food with antioxidant, antibacterial, prebiotic, probiotic and immune-boosting properties. Formula is not able to replicate these live cell traits. Many breastfeeding moms prefer to give their baby breastmilk instead of formula when they need to leave their baby and miss feedings. Since breastmilk is a live medium, it has the potential to grow bacteria if not properly stored. Moms should wash their hands with soap and water before pumping or use an antibacterial hand cleanser. The breasts do not need special cleaning before pumping. The first few drops of milk do not need to be discarded.

Breastmilk can be stored in glass or plastic bottles providing they are BPA free. Using better quality milk storage bags may prevent a higher risk of puncturing the plastic. Breastmilk should be stored in the back of the freezer so it is not exposed to frequent warming due to opening of the freezer door and should also be kept away from the walls of self-defrosting freezers. Bottles and breastpump parts should be disassembled and washed in hot soapy water followed by rinsing with hot water and then air dried or dried with paper towels. They do not need to be sterilized when at home with baby. When mom returns to work and is exposed to germs foreign to her and baby, it is helpful to come home and sanitize them after work. Pump parts and bottles can be sterilized in a pot of boiling water for twenty minutes or sanitized in Medela’s Quick Clean microwaving bags for just three minutes.

Freshly expressed breastmilk can be stored at room temperature for at least four hours and possibly up to eight hours. If the milk is not going to be used in a few hours, it is best to chill or refrigerate it. Breastmilk can be kept in a cooler with an ice pack for up to 24 hours at 59 degrees Fahrenheit. It can be refrigerated at 39 degrees Fahrenheit for four to eight days. If it is not going to be used in 48 to 72 hours, it is best to freeze it. Breastmilk can be frozen at 25 to -4 degrees Fahrenheit for at least three months or up to a year but it may lose some of its protective properties the longer it is frozen. Even if it has been frozen for a year, it is still far superior to any formula.

Some helpful pumping and storage hints: If mom is pumping three times a day at work she may want to give baby two bottles of fresh milk the next day and one bottle of previously frozen milk if she has a large reserve of milk in her freezer. Keep in mind that fresh milk will have the full strength immunoglobulins to fight off recent infections mom and baby have been exposed to.

It is also helpful to freeze different amounts to have different bottle sizes available. A one month old baby will take about two to three ounces per feeding and a two month old may take three to four ounces. Most breastfed babies will level off at four to five ounces per feeding whether they are two months, six months or twelve months old. Another helpful hint is to freeze some breastmilk in an ice cube tray. When the cubes of milk are frozen, pop them out and put them in a freezer strength Ziploc bag. One cube is about an ounce. They can be warmed up separately and used to top off a baby who is still a little hungry without warming up another full bottle and having to waste some of that liquid gold.

Sometimes refrigerated or frozen milk can have a soapy or off odor to it due to the breakdown of fatty acids. Some infants refuse to drink this milk but it is safe to eat if they will take it. This resource does not recommend scalding the milk to eliminate the odor because it can destroy many of the immunological properties of breastmilk.

When freezing breastmilk, make sure to leave space for expansion. Label and date your breastmilk storage bags. Keep in mind that bags are not going to be as accurate as bottles are for determining volume of milk. Your breastpump flanges or breastshields are handy to use as a funnel when pouring milk from a bottle to a bag because if you spill some of your liquid gold you truly will cry over spilled milk!

When mixing containers of milk, always chill them first. If you pump an ounce today, put it in the refrigerator. When you pump another ounce tomorrow, put that one in the refrigerator. When both amounts have chilled, then you can combine them and freeze if desired. Also do not put warm milk on top of frozen milk.

Frozen milk can be thawed by putting it in the refrigerator overnight, by running it under warm tap water or by putting it in a container of warm water or by using a waterless warmer. Thawed milk should be warmed to body temperature over about twenty minutes.  Over heating breaks down some of the protein nutrients and decreases fat content. Microwaving should be avoided due to uneven heating and potential of burning baby’s mouth. It can also lessen the immunological properties of breastmilk.

Thawed milk should not be left in the refrigerator for longer than 24 hours and should not be left out in room temperature longer than two hours. Refreezing thawed milk is not recommended. Once a baby has sucked on a bottle, some bacterial contamination can occur from the baby’s mouth so any milk left in the bottle should be discarded after one to two hours. It is always better to warm up extra breastmilk if needed rather than waste mom’s liquid gold!

Breastmilk can be stored in a cooler with an ice pack while mom is at work. It is safe to put labeled breastmilk in a community refrigerator at work but just make sure someone does not put it on their cereal by mistake!

Uncontaminated breastmilk contains nonpathogenic bacteria that provide natural probiotics for baby’s intestinal flora. Moms can take a probiotic if desired but she does not need to give it to her breastfed baby. If mom has mastitis or nipple yeast infection, she can still store her milk.

If you have any questions about these guidelines, please contact Diane Erdmann by email or calling (402) 707-1696.