Making The Switch: From Breastmilk To Formula At 3 Weeks Old

We were all told that formula isn’t ideal — the concept of “breastfeeding is best” has been ingrained into our minds. It is true that breastfeeding is the best nutrition we can offer our children up to the toddler stage. Healthcare professionals always advocate for breastfeeding. The World Health Organization states that breastfeeding is the “ideal food for infants”.

However, there are certain situations that call for an alternative way to feed. This includes medical reasons, such as certain illnesses or infections, or the use of necessary medications that could be passed to your baby through breastmilk.

It’s a subject of debate on whether a mother should push on with breastfeeding if she’s having a hard time producing milk, or if she’s going to work soon, or is just physically and emotionally tired. Regardless, it’s important to make sure your baby is taking in enough nutrients to grow and develop properly.

Although it isn’t the best nutrition your baby needs at this time, it is possible to switch from breastfeeding to formula at 3 weeks old. Weaning can be started between 3-4 weeks of age, and should be done gradually. As you slowly increase the amount of formula given and decrease breastfeeding time, make sure your baby is comfortable with the transition by observing their behavior and cues.

What a 3 week old should be eating

Let’s do a quick review: during the first month of life, your baby should be fed only milk and nothing else — not even water, cereal, or baby food. Whether as breast milk or formula, milk should be able to provide all the necessary nutrients and calories they will need.

The American Academy of Pediatrics (AAP) recommends exclusively breastfeeding your child for the first 6 months of life. If you decide to switch to formula, make sure that the brand follows the Food and Drug Administration standards and is approved by the AAP. This is to ensure that all your baby’s nutritional needs are covered and in the right quantities.

Reasons for switching

There are a number of reasons why some mothers prefer to feed their babies with formula. Some mothers aren’t able to produce enough milk — their child always exhibits hunger cues and never seems to be satisfied. Others have a hard time with the breastfeeding process itself — maybe there’s difficulty in latching or positioning their baby properly.

Some moms are physically, mentally, and emotionally drained from pregnancy and lack a support group or system at home to deal with daily tasks, on top of handling a newborn.

A possible compromise — pump your milk instead of breastfeeding

A new mom is transitioning from breastfeeding to pumping to feed her newborn baby.

Before solidifying your choice to use formula, there is another option that you may not have considered early on. For mothers who have no difficulty expressing milk but cannot breastfeed for other reasons, you can try expressing your breastmilk and storing them for later use. That way, your child still gets the best nutrition, and you save up on spending for formula.

Ask your doctor for advice

Before you make a final decision, visit your pediatrician and ask for advice. They can provide tips on feeding and alternatives if needed, depending on your situation and circumstances.

When is the best time to wean?

There is no specific ideal time to wean a baby from breastmilk, simply because they are expected to be breastfeeding for as long as they can. The timing really depends on the amount of milk the mother has and the mother and child’s current circumstances.

If it’s important that you wean your baby successfully at a certain date (say, the day you return to work), start the process of weaning around two to four weeks earlier.

How do you wean a weeks old baby?

If you have decided to transition to formula, it’s best to give your infant some time to adjust. Keep breastfeeding for the first 1 to 3 weeks after birth. Slowly introduce formula milk at 3 to 4 weeks of age.

How much milk should be given?

Infants around the first month of life drink 1.5-3 ounces of milk per feeding. Since we’re gradually replacing breastmilk, you can prepare less than an ounce per feed, for the first few days.

What’s the best way to hold my baby during feeds?

Best way to hold your baby during bottle feedings.

When feeding your baby, hold them in a semi-upright position, supporting the head using your arm. Lightly stroke the cheek with the bottle’s nipple to encourage them to drink, then offer the nipple at the mouth. Make sure that the bottle is angled in such a way that the whole nipple is filled with milk. This will prevent your child from swallowing air instead of milk.

The gradual transition

For mothers who already have a dwindling amount of milk, allow your child to breastfeed first for each session so that they still get the optimal nutrients found in your milk. During feeding, top up with formula when there’s no more breastmilk.

If you have no trouble with expressing milk, gradually decrease the amount of time that you breastfeed your baby for each session, and finish with formula milk. For example, instead of the usual 30 minutes of breastfeeding, slide it down to 25 minutes, then feed with formula for 5 minutes. The next day, decrease it further to 20 minutes and add 10 minutes of formula feeds.

Another method is by dropping a breastfeeding session and replacing this with formula feeding. Transition slowly by dropping only one session first, then dropping another one only once per week. If you do this too fast, your child will not adjust well.

During feedings, it’s best to give breastmilk first, to ensure that your child takes in as much wholesome nutrients as possible from your milk. However, if you notice that the transition isn’t as smooth and your baby isn’t interested in formula, try switching it up and introducing formula at the start of the feed. Finish off with breastmilk.

Gradually decreasing the length of breastfeeding per session signals your breasts that your baby has enough milk, causing less milk to be produced. However, this may not work for some mothers. If you find that your breasts are still producing a lot of milk, you can pump it out manually or through a breast pump.

My breasts hurt

During this transition, your breasts may become engorged and painful. Relieve the pressure by pumping out your milk until the pain lessens. If you choose to bottle feed completely, don’t drain your breast completely. This signals your body that the breasts are producing enough milk and that they don’t need to produce any more.

Your baby will most likely fully transition to formula between 1 to 3 months. At this point, they can take around 3 to 4 ounces of milk every 3 to 4 hours.

Make sure your child is okay

A newborn boy is crying while laying down in his crib.

As you’re slowly changing your baby’s diet, watch out for any clues that he or she is uncomfortable with it. If they seem irritable and moody, or wake up and cry in the middle of the night, the transition may be too quick. Avoid overfeeding your child.

Don’t forget to bring your child to their routine clinic visits. Your pediatrician will assess if your child has successfully switched to formula feeds. He or she will also assess if your baby is getting enough nutrients through a physical examination, which includes monitoring your child’s weight.

Try partial weaning

Some moms opt to do partial weaning instead. This is also known as combination feeding. In this type of feeding, breastfeeding continues as usual when the mother has free time. Formula feeds are done in the morning or while the mom is at work.

Before starting with partial weaning, wait until your child is at least 3 weeks old. By then, you will have established your milk supply and a feeding pattern. The optimal timing for starting combination feeds is at 3 to 6 weeks old.

Take caution with partial weaning, though: there’s a possibility that your young one can get confused with your nipple and the bottle nipple. Nipple confusion may cause your child to prefer the bottle over your breast. You can avoid this by feeding formula using a cup instead of a bottle. Cup feeding should only be done with proper assistance and training from a healthcare professional or someone experienced with this method.

Make the transition easier

Sustain skin-to-skin contact when possible

A newborn boy is getting skin-to-skin contact time with his dad.

While feeding your child, part of the process includes skin-to-skin contact. This makes your baby feel secured and comfortable. When feeding him or her using a bottle, make sure you both have physical contact, like you would when breastfeeding.

Ask help from others

Some babies become fussy or frustrated when they feel your hold and embrace, but don’t get the breastmilk that they’re used to. Since your child will be feeding from a bottle, you can employ others to help you out. You can take turns with your partner or relative to feed your baby.

If your baby still refuses bottle feeds from you, request for help. Have your partner or another caregiver feed your baby once he or she has calmed down, becomes distracted, and stops crying.

What if my baby doesn’t like formula?

A newborn is crying and refusing to drink formula milk that dad is trying to feed to him.

What if your child starts refusing to drink, starts pitting up way too much, or becomes too fussy? Is he or she developing vomiting, diarrhea or a rash?

Don’t get too worried if your child seems to be rejecting formula milk. You can introduce it slowly by offering a few drops first to entice him or her, then introduce the bottle right after. Warming up the milk a little bit may also help your baby adjust. Just make sure that it is lukewarm, not warm or hot. Do not use a microwave to heat it up.

If your child develops vomiting, diarrhea or a rash, you can always try a different brand. This is also an option if you feel that your child doesn’t like the taste of formula. Other babies may need special types of milk, such as soy-based formulas or hypoallergenic milk formulas. The AAP recommends an iron-fortified formula for all babies. Consult your pediatrician to help you choose the right one.

Sometimes it’s not the formula, but the nipple or teat that’s causing problems. Avoid fast flow teats or nipples — your child will prefer a nipple that is most like your own. Use a wide, slow flow nipple instead.

Another possible reason for this is that your child is not comfortable with the environment. A quiet room with minimal light can help your baby calm down and focus right back on feeding.

Can I mix breastmilk and formula?

Mixing breastmilk and formula in one bottle is not recommended. Their shelf life is not the same, and their nutrient composition is different. Your child can take in too much of certain nutrients and have difficulty digesting this combination of milk.


Making an important decision can take its toll on you, physically and mentally. The increase in hormones due to pregnancy and lactation doesn’t help either. There may be days when you’ll feel frustrated, overwhelmed, guilty, or overly anxious about your child’s nutrition and health. Don’t forget to take care of yourself, too.

You can ask for support from your family, friends and loved ones as you take care of your newborn. Joining a local or online support group can also help with this transition.

If you feel unusually down and possibly depressed, it’s best to see a doctor. Mothers can experience postpartum depression due to the influx of hormones, coupled with stress coming from taking care of a newborn.


The final decision on whether to continue breastfeeding or not is ultimately up to the mother. It’s most definitely a consideration of the balance between you and your baby’s needs, and a compromise on what works the best for the both of you. Above all, what’s important is that your infant is fed enough — fed is best.

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Sarah is a healthcare writer, motivated by her love of reading books while growing up. She took up human biology and further studies in medicine, in order to fulfill her passion for helping kids. While she isn't a biological mother yet, she has taken two young dogs, named Indy and Obi-Wan, under her wing. She would love to someday travel the world and meet kids from different cultural backgrounds.

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