Episode Transcript
Hi and Welcome to Clerkship Ready – Pediatrics – A podcast aimed at helping you excel during your clinical clerkship in Pediatrics.
I am Paige Howard, and I am a fourth year medical student at the University of Virginia School of Medicine applying into pediatrics this fall.
Today, we will be reviewing what you need to know before your first discussion about infant formula! During third year, you will inevitably get questions about infant formula—which one is “best,” which one to switch to, why it’s giving their baby gas, the list goes on! So let’s make sure that you know what you need to know to help these parents feel confident in feeding their new little baby. In this episode, we will cover the characteristics and types of formulas, why infants might require different types, the correct way to prepare formula and how much infants need, common concerns from parents, indications for changing formulas, and when to transition away from it!
First, let’s talk about why infants receive formula instead of human, or breast milk. While we recommend human milk as the first choice for the vast majority of infants, there are several reasons that infants may get formula. These vary from concern that the maternal milk supply does not meet the infant’s nutritional needs, to the parent returning to a workplace that does not make it possible to sustain human milk feeding, to parent preference. There are very few true contraindications to breastfeeding. These include galactosemia, maternal HIV infection that has not achieved an undetectable viral load, maternal phencyclidine (also known as PCP) or cocaine use, active Herpes Simplex virus lesion, and active tuberculosis. Fortunately, infant formula is an acceptable alternative that provides babies with the nutrients necessary to grow and develop.
Let’s talk about types of formula. When we think about types of formula, we think about 3 different characteristics of formula:
Caloric density: We describe caloric density as calories per ounce. Standard term formula is 20 calories/oz. Infants who are born preterm or have growth failure need more calorie-dense formulas, such as 22, 24, and even 27 calories/oz.
Carbohydrate source: Basically, formulas either have lactose or don’t have lactose as their carbohydrate source. Lactose is made up of galactose and glucose, so those with galactosemia are unable to have lactose containing formulas, including those that are cow’s milk based. Soy formula is often used in its place because it contains either glucose or sucrose as its carbohydrate source.
Protein type: Most formulas are cow-milk based, so the proteins are whey and casein. However, not all infants can digest these proteins, so they require formulas that have different protein compositions. Some formulas called “hydrolyzed” formulas are ones in which the proteins are broken down into smaller protein “chunks” or can even be broken down into individual amino acids, which are hypoallergenic and easily digestible. Other formulas utilize different sources of protein, including soy protein and goat’s milk.
As you can imagine, there are lots of different formulas with different combinations of caloric density, carbohydrate and protein sources. Most healthy infants who are born at term will get your standard, 20 calorie cow milk-based formula with iron. The most common brand names for those are Enfamil and Similac. Even though the manufacturers will tell you differently, the standard formulas are pretty much interchangeable. They will often be advertised as having DHA, which is an omega-3 fatty acid that is integral to brain development. to Another popular choice for term infants is goat’s milk formula, which is an acceptable alternative to cow’s milk, though it is often more expensive.
However, not all infants are born term or are able to digest these formulas, so different types exist for different needs. Preterm infants have higher caloric needs and require higher amounts of various micronutrients, so preterm infant formulas are formulated to provide for these different needs. As we talked about earlier, infants unable to digest the basic cow’s milk fomulas will require hypoallergenic formulas that have hydrolyzed milk proteins. In addition to the conditions we discussed earlier, infants with specific medical conditions, often metabolic conditions, require special formulas that either supply or exclude the contents to fit each baby’s needs. Diseases like phenylketonuria, Maple syrup urine disease, and homocystinuria all require special formulas.
Once you know about the different types of formulas, it’s helpful to know what forms they come in and how to mix formula correctly. The most common and least expensive form is powder. This comes in a big tin and gets mixed with water prior to feeding, usually 2 oz of water and 1 scoop of formula powder. You can also find the formula in a liquid concentrate, which is mixed with an equal amount of water. And finally, you can also find the formulas in a ready to feed form, which does not require any mixing but is also the most expensive. This information can be important when talking with parents, and you should always ask about what type of formula the baby is getting and how it is being mixed. This is particularly important when a patient is not following their growth curve! One common reason that a baby is not growing along their growth curve is because the parents have accidentally been mixing the formula incorrectly. Always ask the parent to show you their formula (if they brought it) and ask them how they mix it. Ask specifically what scoop they use, and how they measure the formula. For instance, do they level off the top of the formula powder, or do they use heaping scoops? If they are mixing it directly in the bottle, make sure that they are putting the water in the bottle first, and then adding the formula. Often, you can correct that mistake quite easily with a bit of teaching and get the infant right back on track!
Another important thing to consider is how much formula is the right amount. It is difficult to say how much volume is the right amount for an infant because infants of different ages will take different volumes and will require feeding at different intervals! A good rule of thumb is that infants require between 120-150 calories/kilogram per day. This usually starts at around 1.5-3 oz every 2-3 hours in the newborn period, and the volume and feeding interval will increase with age and size.
Now that you know all of this, you’re well on your way to engaging in a productive and informative chat with a new parent.
BUT it’s helpful to know the common myths that cause parents to switch formulas and how you can help dispel any concerns. First, let’s talk lactose intolerance. This is a common concern for parents and a common reason that parents will want to change from a cow milk-based formula. They will notice the infant has some gas, their stools are a bit looser than expected, or that they have some fussiness with stooling, and they will wonder if it is lactose intolerance. The best thing you can do is remind parents that true congenital lactase deficiency is a very rare disorder and, in infants, it will usually present with very severe diarrhea. What we adults experience as lactose intolerance occurs later in childhood. In addition, while developmental lactase deficiency can occur in premature infants, this condition only lasts for a short time after birth and the majority are still able to consume lactose-containing formulas. While infants can develop lactase deficiency after suffering from a gastroenteritis, this is temporary and will resolve on its own with time. Arming parents with these facts can often be very helpful in easing their concerns about their baby’s feeding.
Another common concern that comes up for parents is that their infant is having increased spit ups, and they worry that the infant is no longer tolerating the formula. This often occurs around the 4 month mark because the volume of the spit ups starts to increase at around that time, but the usual cause is that the baby is taking in more formula at a time rather than actually not tolerating it. And sometimes the baby has taken in more than they need, and the extra comes out as spit up. As long as the baby is growing and developing appropriately and their behavior is at baseline, you can reassure the parents. If babies have bigger poops or bigger spit ups, it’s often because they’re just getting bigger!
Similar to the spit ups, parents may also get really concerned about the infant’s gassiness and stomach discomfort after feeding. They often take this as a sign that their child’s GI tract cannot handle the formula. In reality, gassiness is a normal part of infancy due to the fact that they’re not very mobile and they often have not developed the best coordination for stooling. It requires contraction of the abdominal muscles to push stools through the intestines and simultaneous relaxation of the pelvic floor muscles and external anal sphincter to successfully pass a stool. That is a lot to ask of an infant. In addition, since a young infant can’t sit up or stand yet, they can’t take advantage of gravity, and it’s going to take a little more straining to have a bowel movement. Things that can help with this are bicycles and giving them some tummy time. You can do the bicycles by lying the infant on their back and cycling their legs to create movement that helps with bowel motility.
Once you have reassured the parents that their concerns are likely not reason to switch formulas, it's important to also let them know that switching formulas in rapid succession can lead to spitting up and GI upset, which leads to more switching. Babies can’t adjust to the new formula very quickly, so their bowel movements may be looser or they may be gassier, leading parents to feel the need to switch again! Encourage parents to stop switching and stick to one. It usually does not matter which one if the patient does not have any specific medical needs, so just encourage the parent to stick with the most affordable, most available formula or the one that they are currently using.
So now let’s discuss reasons to actually switch formulas. If a patient has galactosemia or an allergy to cow milk protein, you should switch to a lactose free formula. Galactosemia is tested for on the newborn screen, but it presents with trouble feeding, vomiting, failure to thrive, jaundice, and cataracts. Most infants with milk protein allergy present with blood in the stool, because they have developed an allergic proctocolitis. Rarely, more severe milk protein allergies can present as hives or even anaphylaxis. For these infants, you should switch to a hydrolyzed formula. And of course, if your patient has any of the metabolic disorders that require a special formula, you should switch to those to prevent problems such as seizures or profound intellectual disability. These outcomes are a result of a buildup of amino acids that cannot be metabolized and can cross the blood brain barrier, causing cerebral edema or having cytotoxic effects.
Finally, it’s important for you to know that infant formula can be weaned at 1 year of age and replaced with cow’s milk, usually whole milk. This means that the parent can replace formula with cow’s milk. Often times, it can be easiest to finish the cans they have already purchased and slowly introduce cow’s milk in its place. We recommend whole milk because it has extra fat, which the 1 year old needs for continued brain growth. It is important to stress that infants under the age of 1 should not get any cow’s milk at all. Not only does cow’s milk lack the proper amounts of iron, vitamin C, and other nutrients for young infants, but also its high concentrations of protein and minerals will stress infant kidneys. That’s why we wait until 1 year. At that point, I also try to decrease bottle use! I recommend that, when they start cow’s milk, start with it in a cup so that’s what the child is used to. Not only does that make the transition to the cup easier, the cup is also better for dental health than the bottle, which allows milk or formula to pool in the mouth and around the gingiva. This creates a breeding ground for the bacteria that lead to tooth decay.
That was a lot of information, but hopefully you can take some of this with you into your first formula talk with parents, giving yourself confidence as well as giving the parents confidence in helping their infant grow and develop in their first year of life.
OUTRO:
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