Can you freeze 4 day old breast milk? 

In this brief guide, we’ll address the query “Can you freeze 4 day old breast milk?” Also, we’ll explore how breast milk should be stored, what breast milk is made of, and what are the dangers of feeding infants breast milk that hasn’t been properly stored. 

Can you freeze 4 day old breast milk

Four-day-old breast milk can be frozen, but only if it was kept in refrigeration during said time. 

Breast milk, like any other type of unpasteurized or opened milk that is left unrefrigerated, or refrigerated for too long, will spoil and give off a foul odor and rancid taste. In such a case, it should be discarded just as soon as it is discovered, 

Briefly refrigerated milk on the other hand, while it may not be the freshest after four days, can be stored in the freezer and preserved for 6 to 12 months, but freezing it will not restore its freshness, and will only serve to preserve it in its current state. 

How should breast milk be stored? 

Breast milk should either be refrigerated or frozen to keep microbes at manageable levels and to prevent other components such as fats and other bioactive molecules from denaturing (breaking down).

However, freshly pumped breast milk, once bottled, can remain at room temperature (15-25°C) for up to six hours, although if the room is slightly warm, leaving it out for no more than four hours is not recommended. 

Breast milk that will be fed to a baby in the short term can be refrigerated, where it can keep for up to four days if placed in a tightly sealed container. Using refrigerated breast milk is as simple as taking it out and heating it in a baby bottle, using a microwave.

Surplus breast milk that won’t be consumed within 4 four days can be rationed into vials or freezer-resistant bottles and be stored at subzero temperatures. 

As it expands, containers should not be filled to the brim and should have air space between the milk’s surface and the container’s lid. Once frozen, it can be kept for up to one year but is best fed to a nursing infant within the first six months of being frozen. 

When freezing breast milk, it’s important to bear in mind that it should be rationed, rather than frozen in bulk, as once it’s been thawed it must not be refrozen. 

Defrosted breastmilk can be kept for one day in refrigeration, and approximately 2 hours at room temperature, during which it should be promptly consumed.

What is breast milk made of?  

The exact composition of breast milk varies from individual to individual, diet types, and even nutrition stages of infants, but generalizing, breast milk is constituted by many bioactive molecules, which are suited to an infant’s nutritional needs. 

As breast milk is the first food most babies will ingest, it contains proteins and other substances that help prepare babies’ digestive systems for solid food that they’ll be fed once they’ve grown. 

Notably, breast milk is full of molecules that help babies develop their first line of defenses against infections from microbes, and maladies such as inflammation and irritability, while also stimulating the maturation of their immune capabilities. 

Breast milk’s exact composition changes between mother to mother, and even at the feeding stage; the earliest lactation secretions may be rich in colostrum (which newborns drink), while late-stage lactation milk, also known as mature milk, is produced about two weeks after a woman has given birth. 

There is also an intermediate type of milk, produced about four or five days after giving birth, which is known as transitional milk, that begins to show decreasing concentrations of colostrum. 

Colostrum, which is the first milk a woman produces, has a high concentration of white blood cells and antibodies such as immunoglobulin, lactoferrin, leukocytes, and growth factors. 

Additionally, colostrum may have a pinkish coloring, due to some carotenoids that may be present. Colostrum also contains vitamin A, and the essential minerals copper and zinc, which stimulate the development of a baby’s immune system. 

Changes in breast milk’s composition occur over the first few days, and weeks of lactation, and mature milk may have different concentrations of fatty acids, sugars, proteins, and other bioactive components. 

However, despite the plethora of health benefits breast milk provides infants with, it may also be a source of contaminants that may be present in the mother’s system. 

Organic contaminants such as dioxins, pesticides, drugs, and even heavy metals that may be liposoluble (soluble in fat) can be passed on to newborns through breast milk. 

What happens if you feed an infant breast milk that hasn’t been properly stored? 

Other than an unpleasant taste and smell, breast milk that hasn’t been properly stored can cause an upset stomach, reflux, vomiting, and in more severe cases, abdominal pain and fever.

Milk that has been left out for too long may go sour and may be contaminated with microbes, which may cause infants to feel discomfort and experience symptoms of intoxication

Milk that has separated (with a fatty layer on top and heavier sediments at the bottom) should be closely inspected for its odor and taste. At the slightest hint of souring, it should be thrown out. 

Infants are especially susceptible to dehydration and malnourishment, so we recommend that if our readers suspect that breast milk is subpar. Which is to say, that the coloring, consistency, odor, and taste seem off, it’s best to discard it and feed a baby with fresher milk. 


In this brief guide, we’ve addressed the query “Can you freeze 4 day old breast milk?” Also, we’ve explored how breast milk should be stored, what breast milk is made of, and what are the dangers of feeding infants breast milk that hasn’t been properly stored. 


Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.