Fortifying Breast Milk: The Reasons and the Risks

What does fortifying breast milk even mean? And isn’t breast milk already a perfect food for human babies? We talk about that all the time. There is no more perfect and human-specific food for human infants than human breast milk. So, it might seem confusing to hear discussions about fortifying breast milk.

What Does “Fortifying” Mean?

Fortified foods have extra nutrients added to them to improve their nutritional value. In the case of breast milk fortification, it usually means that a medical care provider adds a commercially made supplement or “fortifier” to the breast milk. It might be a powdered fortifier, or a liquid. Fortifiers can be made using cow’s milk, or more recently, human breast milk. In some cases, infant formula is used to fortify breast milk, but not usually.

So, if breast milk offers perfect nutrition, how and why would fortification be useful or needed?

Premature and Very Low Birth Weight (VLBW) Babies

The main prescribed use for breast milk fortification is for VLBW babies. These babies are usually born very early. They are often born before the 3rd trimester and have very tiny bellies and very special needs. When a baby is very small, their belly can not hold much milk. They are also very immature and burn calories more quickly due to the amount of energy needed just to keep their body temperatures up and survive. For this reason, every drop that goes into their tiny bellies might need to be as calorie-rich as possible, which is even more than regular breast milk needs to be for most babies.
But not ALL preterm babies need milk fortifiers. Many babies who are born somewhat early and small will still grow and thrive on breast milk alone. There are also some cases where a full term baby might need breast milk fortification. If a baby is especially small and fragile due to other medical conditions, fortifying the milk might be necessary.
The important thing to note here is that you only do this under very special circumstances and under the supervision of a clinical team. The doctors and nutrition experts work together to tailor a feeding/fortification plan for the infants needing special care. Milk fortifiers are not easily available to the general public. These are medical nutrition products that are purchased by hospitals through specialized medical supply distributors.

What About Using Formula as a Fortifier?

There have been a lot of conversations going around about adding formula to breast milk as a “fortifier”. This might be useful in some very special cases, but should only be done under the recommendation and supervision of your medical care provider. If it is deemed necessary, they will give you a very specific formula to use and dosing information. It should be treated as a medically necessary prescription and only carried out as directed.
It is also a good idea to seek additional advice from a lactation consultant (IBCLC) and Registered Dietician (RD). Most people who consider breast milk fortification, do so because their babies are not gaining enough weight. A pediatrician might recommend it, or they might hear about it from a friend or online. It can be safe to fortify breast milk with formula, but it can also cause problems when done incorrectly or unnecessarily. For that reason, it’s so important to get a clear idea of the reasons behind the slow weight gain. Your doctor can give some ideas, but seeing an IBCLC is also an important first step. They can examine you and your baby, do a weighted feed, and ask all the right questions to help you to find the cause of the problem. Once you know the cause of the slow weight gain, there are usually better strategies than milk fortification to fix the problem.

Causes of Slow Weight Gain

In most cases, babies gain weight too slowly because they are either not getting enough milk or they’re not getting enough calories. This can happen for a lot of reasons including:

• Bad latch – The baby might have trouble holding on to the breast correctly. This can happen for a lot of reasons. The baby might have a structural problem in the mouth that limits their ability to move their tongue or hold on to the breast. The baby might have a shallow latch and just needs a little help learning how to hold on.
• Weakness or low muscle tone – A baby might have a hard time draining the breast because of weakness. They might get tired and give up quickly. It could just be immaturity or a bad latch, but it’s good to find out for sure, because it could indicate a bigger problem.
• Low milk supply – Sometimes there is not enough milk in the breast. Milk supply can be low for a lot of reasons, and it’s important to take steps to increase it when it is. Fortifying bottled breast milk will not help increase milk supply, and can make it worse, so it’s important to find out.
• Improper ratio of lower fat to higher fat breast milk – Some people naturally have lower or higher calorie breast milk, and babies usually still get what they need either way. They might need to eat more often or for longer, but it usually works out. However, sometimes they aren’t getting everything they need. The first amount of breast milk a baby gets is usually very hydrating, but lower in calories. At the end of a feeding, as the breast is draining, the milk gets fattier and more calorie dense. It’s important to allow babies to get ALL of the milk they can at each feeding. Sometimes, cutting a feeding short can mean a baby is not getting the fattier milk and all of the calories they need.
• Health problems – Sometimes babies lose weight because of an underlying health condition. If you have visited with an IBCLC to determine a cause for your baby’s slow weight gain, and they can’t find one, it’s a good idea to visit with your pediatrician. An IBCLC will often make a referral and communicate with your doctor to be sure the issue is communicated.

Other Ways to Improve Weight Gain

Instead of resorting to fortifying your breast milk (which can have some downsides, see below) you can instead do some things to address the root causes of the problem.

• Address the latch.
• Address low milk supply issues
• Breast massage – If your baby is latching well and you have good milk supply, you can help your baby get more calories at each feed by gently massaging your breasts before and during the feed. Fat molecules that might be stuck on the walls of the milk duct can detach and enter the milk supply so your baby is getting a higher fat/calorie milk.
• One breast at a time – If you’re giving your baby both breasts at each feed, you might also try feeding from one breast per feeding. Encouraging your baby to stay attached as long as they want can help them get more of the fatty “hindmilk” which is higher calorie. If they do that and are still hungry, you can move to the other side. But don’t cut them off to ensure that they feed from both breasts. This is often not necessary, and might mean your baby is not getting all of the calories they can.
• On-demand feeding – Young babies don’t need to be on a feeding schedule. They have tiny bellies at first. They fill and empty quickly, so it’s important to feed as often as they need. Also, your milk changes throughout the day. Sometimes it’s higher in calorie content, and sometimes lower. It’s important to ensure that your baby is getting all of it. And your milk supply responds to frequent feeding, so feeding often means you establish a great milk supply.

Potential Downsides to Fortifying Breast Milk

When you can determine the cause of a baby’s slow weight gain, there is usually a permanent solution. If your baby has a bad latch, fixing the latch can help your baby start gaining weight quickly. If your milk supply is low, taking steps to address that can mean your baby starts gaining weight. Finding the root cause of the problem and taking steps to address it means the problem is fixed and you don’t have any more problems. If you don’t determine the root cause and instead just start taking steps to address the symptom (slow weight gain), you might end up causing a new problem or set of problems.
Adding formula to bottled breast milk might help your baby gain weight, but it can also lead to some complications that you’ll then need to deal with. For example:

• Some babies will experience stomach upset with the addition of formula. Your baby might not tolerate some component of it well, or it might cause an imbalance of nutrients. Also, breast milk does the work of helping your baby establish a healthy gut microbiome. Until that is well-established, introducing other foods can cause stomach upset. That might look like lower appetite, increased spit up or reflux, constipation or fussiness. This can sometimes lead to a decrease in feedings which can end up causing another slow weight gain problem.
• Your milk supply can suffer if you don’t replace those full at-the-breast feeds with pumping. Any time you replace your baby’s breast milk with something else is calories they are not getting from you. To maintain a good milk supply, you need to give your body the signal that your baby is asking for food as often as they need it. If you replace a body feed with a bottle feed, you’ll need to replace that body feed with pumping or your milk supply will scale down, and then you will become dependent on the formula.
• Having less direct breastfeeding limits the communication between your body and your baby. This is an amazing and important component of direct breastfeeding. You get the full benefit of that coordination. When your baby is at the breast, there is an exchange of  saliva and microbes that sends signals to your body. Your body picks up on those signals from the baby and can create a milk recipe that is customized to your baby’s needs. If your baby is dehydrated, your body can pick up on that and the milk will be higher in water. If your baby is sick, your body can pick up on that and add antibodies to the milk to help them recover. It’s an incredible system and best to take advantage of it whenever you can.
• There is increased cost to using formula. Even if it’s for a short time, you might need to consider the cost, but especially if there ends up being a dependency on formula, it could mean significantly more cost for your family.
• Adding formula to bottled breast milk changes the nutrient ratios. Breast milk provides an ideal ratio. Formula on its own can also have a good ratio. However, when you mix them, the nutrients can be out of proportion. Breast milk has different ratios depending on the time of day, so it’s not possible to predict what it will be like every time. That imbalance of nutrients can cause issues like dehydration, vitamin deficiencies, mineral imbalances, creating symptoms such as fewer wet diapers, bloody stools or constipation.

Things You Might Try First

If you are worried about your baby’s weight gain, see an IBCLC. They can help you get to the bottom of it and give you advice that might be simple and effective. You might be advised to:

• Feed your baby more often.
• Feed your baby more at certain times of the day.
• Ensure that your baby feeds at each breast for as long as possible.
• Include breast massage into your routine.
• Start a customized pumping routine.
• Give your baby additional pumped breast milk or liquid formula after each feed, or after some feeds, for the extra calories.
• Monitor your baby’s weight gain with a rented pediatric scale or by visiting the lactation clinic for checkins.

It can be hard to trust that things will work out, especially if it’s your first time or if things aren’t going exactly as someone else told you it “should”. Remember that every baby is different. Some babies are just small. Other babies will gain weight slowly and still thrive. Some babies need to eat often, others not as often. They might need to eat for longer periods, or they might finish quickly. Also, every parent is different. You might have lower calorie milk or higher calorie milk. You might make a surplus of milk, or just enough to feed your baby.

There will never be a perfect system or set of “rules” to follow that works for everyone. It’s ok to trust yourself and if you suspect anything, seek help from a lactation professional. It’s best NOT to follow internet trends or well-meaning advice from family and friends. It might be good advice for some, but really bad advice for someone else.

References

Fortification of Human Milk for Preterm Infants: Update and Recommendations of the European Milk Bank Association (EMBA) Working Group on Human Milk Fortification

Individualized Target Fortification of Breast Milk: Optimizing Macronutrient Content Using Different Fortifiers and Approaches

Dilemmas in human milk fortification – PMC