What's in your milk?


Your milk is so specific to you and your baby’s needs, it’s quite magical really. 

In this section, we’ll walk you through what’s in your milk, what can affect it, and what to use if you’re not able to make enough of your own. Here are the topics: 

🍼 What is my milk made of?

🍼 Factors that affect what’s in your milk

🍼 How your milk changes

🍼 What’s the ‘best’ milk for my baby?

❔Common questions


What is my milk made of?

Your milk is different from cow’s milk. You already knew that though. 

All mammals make milk, which is made from four basic components: 

  1. Lactose
  2. Water
  3. Protein
  4. Fat

The proportions of these four ingredients change between species. 

For example, human milk tends to be higher in lactose and water, and lower in protein and fat than other mammals. This low protein and fat means we need to feed our babies more often than other mammals whose fat content is higher. 

Now unfortunately, especially if nursing isn’t going well, we also can’t simply feed our babies milk from animals or vegetables with higher protein and fat. There are other components alongside these ingredients that are specific and needed for human babies to develop and grow. 

This is why formula was developed – to try to create food that closely mimics human milk. It’s not quite there yet, but it’s better than other milks. Read more about the ‘hierarchy’ of infant feeding

What’s in your milk is very complex, and like most topics in the area of breastfeeding, could really use more funded research. Despite this, the researchers working in this area certainly pack a punch. 

Here is an excellent and recent collection of papers looking at breastfeeding and lactation if you want to go down the rabbit hole of what’s in your milk and how it changes over time. 

Factors that affect what’s in your milk

All sorts of factors affect the make-up of your milk. 

Time of day alone, can change the amount you produce, and also the fat and lactose content. 

On top of time of day, any of the following can affect your fat content: 

  • how much milk you have available
  • how much you have “emptied” your breast
  • how much time you have between pumping/feeding
  • how quickly you’re able to remove milk (i.e. did it take 5 minutes or 20 minutes to feel finished)

How your milk changes

Your milk composition changes over time. 


Your first milk, called colostrum, appears to have higher protein but lower fat and lactose than your mature milk. 

But then as your baby grows, the fat content in your mature milk also increases. So for the same amount of milk after 2 years, you have more than double that fat content than in the first year. If you are pumping, you don’t need to be pumping increasingly large volumes to keep up with your child. Your breast milk may do that for you by increasing the fat content (and energy content).

Both milk volume and milk composition changes over the day. During the night and early morning, prolactin tends to be higher, and you may notice that you collect more milk in those sessions. 

But the composition of your milk changes over the day too. 

This study indicated that fat content is highest in the early afternoon, and that when milk volume is low (and lactose is low), that fat is high. And vice versa. 

The ‘best’ milk for your baby?

As you have read (and probably received a fair bit of unsolicited advice and societal pressure for), we know that feeding at your breast is ideal for your baby. 

First your breast milk contains what your baby needs to grow. Second, there’s some seriously wonderful stuff happening when your baby is at your breast that isn’t to do with your milk. For example, by being at your breast, your baby is helping to trigger hormone responses in you that help to create and push out more milk. You and they are also benefiting from skin to skin contact.

But, we also know that although many of us want to feed our babies most of the time at the breast, we can’t or aren't able to do it, and don’t have access to the right support to make it happen.

It’s not just a few people in this category. 

In Australia, almost everyone (96% of people) tries breastfeeding at birth. But by six months 35% are feeding only breast milk to their babies, and 74% are feeding at least some breast milk. 

In the USA, the rates are lower. About 75% of people start breastfeeding, and by six months 13% are feeding only breast milk to their babies and 43% are feeding at least some breast milk. 

In many cases, support from a specialist lactation consultant (IBCLC) and a supportive environment at home and work can help. If we can’t access help, or that help isn’t….helping, then thankfully there are still options for feeding your baby. 

People in the lactation field refer to these options as the infant feeding hierarchy. 

Why hierarchy? Because some are better than others.  

Before you read through the hierarchy, remember that: 

  • the feeding options are listed in order of best food for your baby (not necessarily your mental health)
  • sometimes they aren’t available to you, or you need to do a mix of them 
  • they are for a healthy, term baby

Here’s the hierarchy: 

  1. Breast milk via feeding directly at the breast 
  2. Breast milk via pumping
  3. Donated breast milk from another mother, where the donors are screened, and milk is screened and pasteurised, and transport and storage done to CDC guidelines
  4. Formula
  5. Soy Formula. Lower than regular formula because of concerns about estrogenic effects

Never: cow’s milk, goat’s milk, plant’s milk or homemade formula. Your baby’s needs are quite specific, and you can risk causing electrolyte imbalances, deficiencies and other conditions. 

Common questions on your milk

Have we not answered your question yet? 

Here are some common questions we hear on this topic. 

Should I test my milk?

Sure, you can test your milk. BUT. Be aware that your milk changes so much with time and other factors. This means that one sample doesn’t represent your milk all the time. If you’re planning to make changes to how you are pumping or nursing based on the results, then this would be something to do with the support of your doctor or lactation consultant. 

What about foremilk and hindmilk?

There is a concept out there that you need to pump or nurse for a certain time to access the fattier hindmilk. 

This idea came from a study in the 60s, when they looked at fat content from one woman expressed with a breast pump. She had higher fat content in the second half of her pump, than in the first half of her pump. This may have been true from her, but this idea doesn’t necessarily translate to everyone every time. 

Milk composition is quite different from person to person, and also time of day, space between feedings and how much milk you have available. More recent research suggests that actually fat content is more to do with how quickly your baby or pump can remove milk from your breast. 

Does one of my breasts make ‘better’ milk than the other?

It’s very rare to have both breasts create exactly the same volume. But that doesn’t mean the quality of the milk is different. One study found that despite different volumes, fat content was the same in both breasts. 

If I’ve had breast surgery, will I still make milk?

You can still make milk. You may have less chance of being able to make milk due to damage to the nerves that run through your areola. Those nerves are important for sending the signal to your brain to release prolactin and oxytocin to make and push out milk. 

Depending on the method your surgeon used, breast reduction can involve removing nerves, circulatory system and ducts. And breast implants can increase pressure within your breast, regardless of whether they’re placed behind or in front of your breast tissue. 

While people who’ve had breast surgery may have lower rates of breastfeeding, you can still breast milk feed your baby. Take a look at this study, which looked at the effect of breast reduction surgery on breastfeeding

Should I drink more milk to make milk?

Nope. Your breastmilk is produced by your body when it is removed from your breast. Remember supply and demand? You need water to make it, but not more than you need regularly to stay hydrated. 

🤔Still haven’t answered your question? Contact us at support@milkdroppumps.com 

Next up: learn about How babies feed