Ways Your Breast Milk Changes Throughout Breastfeeding

Ways Your Breast Milk Changes Throughout Breastfeeding

Ways Your Breast Milk Changes Throughout Breastfeeding

Meeting your little one’s ever-changing nutritional needs (and tastes!) can be a challenge. However, if you’re a breastfeeding mom, that’s one thing you don’t have to worry about. Whether you breastfeed for two months or two years, your breast milk is never the same two days in a row. 

What’s Breast Milk Anyway?

Have you ever stopped to think about what breast milk really is? It’s an incredible, unique substance that our bodies produce. Breast milk is water—of course—but also carbohydrates, lipids (fats), and proteins. 

Breast milk is 90% water, which is critical for hydration, regulating body temperature, and protecting organs. The hydrating capacity of breast milk is why your baby doesn’t need additional sources like water. 

The carbohydrates in breast milk help provide energy, but also promote healthy bacteria in your baby’s gut and fight off diseases. However, most of the calories in breast milk come from the fat in the milk. Fats deliver essential fatty acids that help your baby’s brain, nervous system, and vision development. They also help deliver those delicious chunky baby fat rolls—breast milk is responsible for your baby’s weight gain. 

Proteins, on the other hand, build and strengthen your baby’s body and help produce critical hormones, enzymes, and antibodies that make breast milk so special. 

  • Antibodies help fight off all kinds of ailments, from ear infections to the common cold. The primary antibody in breast milk is secretory immunoglobulin a (SIgA). This substance coats the lungs and intestines to keep germs at bay.
  • Hormones support growth and development, metabolism, and other critical physiological functions. Hormones also play a critical role in making breast milk. Think: prolactin, oxytocin, thyroid hormones, and growth factors. 
  • Enzymes aid in digestion, support immune system functions, and more. 

What Are The Big Changes in Breast Milk?

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Nutritional Composition

Your breast milk goes through three main stages: colostrum, transitional milk, and mature milk. Each stage provides exactly what a baby needs at a particular time. 


Sticky, gold, and rich in immunological benefits, colostrum is the very first breast milk you produce. It jump-starts your baby’s immune system response by helping them grow healthy gut flora and preventing harmful bacteria. It also helps your baby pass meconium—their first bowel movement. 

You might not produce much colostrum, but you don’t need to. Your baby’s tummy is tiny, and the colostrum packs a lot of fat to keep them satisfied. 

Transitional milk

Your body will make colostrum for a few days, but your postpartum drop in progesterone will trigger your milk to come in. The quantity of transitional milk is much greater. Many moms notice fullness or discomfort in their breasts as their milk comes in. (Massage can help relieve this!) 

Transitional milk is creamy and rich. Transitional milk has more fat and lactose, but less protein. The antibodies and enzymes in transitional milk shift, as well: Lactoferrin and SIgA appear at lower levels, but bacteria-killing enzymes increase. 

Mature milk

After a few weeks, your breast milk is officially matured. It will look less creamy — it might even look watery at times — but it’s no less perfect a food for your baby. 

Like colostrum and transitional milk, mature milk is a living fluid. It's constantly adapting to your baby's needs. Mature milk can provide anywhere between half to all of your baby's nutritional requirements (depending on their age, of course.). It contains complex fats, sugars, and proteins that support the rapid growth that your baby is doing. 

During Each Feeding

When you pour a glass of milk — almond milk, cow’s milk, whatever store-bought variety you prefer — all the milk comes out basically the same at the end as it does the beginning. It’s consistent. 

Breast milk doesn’t work that way. The milk you produce at the beginning of a pumping or nursing session — known as foremilk — is different from what you produce at the end — hindmilk. They’re both breast milk and they’re both valuable, but their composition is different. The change between fore- and hindmilk is gradual, marked by a slow increase in fat content. 

Breast milk also changes depending on when you’re nursing or pumping. Middle-of-the-night sessions yield more milk and milk that is higher in serotonin. (Great for getting little ones on a good sleep schedule!)

Supporting Healthy and Growing Babies

When your baby is sick, your breast milk knows it. Whether through nursing or through close contact like kisses, your breast milk interprets their immune system and adapts to it so they get the nutrition they need to get healthy. And if you get sick? Your breast milk responds by providing antibodies to that very illness for your baby. Amazing!

But breast milk doesn’t just change during illnesses. It changes during growth spurts! The increased demand for nursing or bottles of expressed milk leads to more frequent feedings, which can increase the fat content of your milk. 

Quantity (But Not Quality) 

Once you begin introducing solids to your baby, you may find your milk supply drops a little as your little one begins to explore their new menu options. For breastfeeding into the busy toddler years, mamas may find their supply dips even more when their menstrual cycle returns and nursing and pumping routines change.

Don't be alarmed—that's totally normal! Just know that your little one should receive breast milk as their primary source of nutrition through the age of one (as per the American Academy of Pediatricians) or two (as per the World Health Organization). 

But even though your little one's palate is expanding and they're getting busier and busier, your breast milk still packs a punch. In fact, once your little one enters toddlerhood, your breast milk actually develops more antibodies and higher fat content. 


*Image by Amada44

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