There are many reasons why women combination feed their babies—that is, feed their babies with a mixture of breastmilk and formula. At their core, however, these reasons come down to two main factors:

Combination feeding out of choice
Combination feeding out of necessity.

Let’s look at both of these scenarios and go through some strategies that will increase your chances of successfully maintaining combination feeding in the medium and long term.

Combination feeding out of choice

Some families make the decision before their baby even arrives that they would like their baby to have the benefits of breastfeeding, but mum doesn’t want or feel able to take on the commitment of full-time feeding. In our experience, this path can be successful for many families when the necessary steps are taken in the early days and weeks to protect both types of feeding.

Have realistic goals. To include breastfeeding in your journey, we have to acknowledge some biological facts about how milk production works. For example, wanting to fully breastfeed during the day and fully formula feed at night is unlikely to work. Frequent milk removal is necessary for the continued production of breastmilk. If you are removing milk frequently during the day, your production will be strong. You will then start to feel horribly uncomfortable at night as milk production continues, but milk is not removed. This discomfort resolves after a few days, but for an unfortunate reason: the long periods of time where milk wasn’t being removed have started to reduce your overall supply. In another few days, you may find your baby dissatisfied after a daytime breastfeed, so you offer a top-up from the bottle. In this scenario, more and more top-ups are introduced until breastfeeding either becomes a very small part of your feeding journey or is stopped altogether.

This could have been avoided with the introduction of at least one breastfeed in the midnight–6 a.m. window. Feeds at this time are particularly important for overall supply and would also break up the night so that there isn’t that long a period without feeds. Unless you have full-time night help, the chances are that you (mum) will be responsible for at least one of the night feeds in any case, so we would simply make that feed a breastfeed.

Establish breastfeeding before introducing the bottle. Breastfeeding is both a natural and a learned behaviour, and some babies struggle with learning two parallel feeding methods at once. Our advice for women wanting to successfully combination feed is to get the latch effective and comfortable before introducing a bottle. This doesn’t mean waiting the full 6 weeks until feeding is ‘established’, but just until the baby is at least back up to birth weight and feeding is going well. At this point, you can evaluate what aspects (or feeds) are not working for you and introduce replacement bottle feeds at those times.

Use a baby-led bottle-feeding method. This means allowing your baby to control the pace and volume of the feed (see article 26 for a full explanation on how to implement baby-led bottle feeding). This feeding method will allow your baby to decide how large each bottle feed should be and will also enable them to use as similar skills as possible to their breastfeeds.

Don’t skip two breastfeeds in a row. Every family will decide what level of combination feeding works best for them. For some families, it will simply be one feed per day, so that mum gets some respite and dad can get more involved. For others, it will look more like a 50-50 arrangement. Whatever arrangement you choose to go for, try to make sure that there are breastfeeds at least at every other feed (i.e., not two formula feeds in a row). Once you drop breastfeeding below every other feed level, it can be hard to sustain enough supply for those remaining breastfeeds.

If you follow these general guidelines, chances are you can have a long and successful combination feeding journey with your baby.

Combination feeding out of necessity

For some women, there are supply issues that require supplementation with formula in either the short or long term. The vast majority of supply issues are related to feeding, which has a tricky start and can be overcome with support. This article is too general to go into the vast number of specific cases, and so it is also advised to seek support from your local lactation consultant. In around 5% of cases, we know that women have biological factors that make exclusive breastfeeding infeasible. In these cases, it is also good to get support from your local lactation consultant to ensure the best possible outcome for you and your baby. In all cases, though, there are some general guidelines that can ensure your baby is getting the necessary balance between breast and supplements.

Breastfeed when your baby is calm and alert. We want the breast to be a positive place for your baby, so we want to avoid ‘fights’ at the breast, and we also want them to have the stamina for feeding effectively. This means that you may need to experiment with the timing of the breastfeed versus the top-up. There are a few patterns you can play with:

Breastfeed first. If your baby is alert and has stamina (usually meaning they are not significantly below birth weight), you may get the best breastfeed from them by breastfeeding at the beginning of a feed. Feed on one breast for as long as they are doing good, deep sucking. When these go to just ‘nibbly’ sucks, switch to the other breast. Keep switching back and forth like this until you’re no longer getting good sucks out of either breast or you’ve reached around 45 minutes. Then, give them a bottle in a baby-led way (see article 26 for more details), for the lowest volume that will keep them satisfied.
Breastfeed last. This works well on babies who are low on stamina and who often fall asleep very quickly at the breast. The idea is to give them their usual amount (or even 5–10 ml less) of formula so that they get a little burst of energy. You should then find that you get a more effective breastfeed from them after the bottle. Use the aforementioned breast-switching method until they are satisfied.
Breastfeed in the middle. This pattern tends to work best when there are significant volumes of formula needed. In these cases, an initial breastfeed can frustrate a hungry baby looking for a faster flow, and a breastfeed at the end of the bottle can make them unmotivated to ‘bother’ to get their dessert. So, we would look for the sweet spot here of giving a little formula to take the edge off their hunger, before using the breast-switching method until they are no longer drinking well at either breast, and finally giving more formula until they are satisfied.

To move back to more breastfeeding. Assuming that you are among the majority of women for whom these formula supplements are a temporary requirement, you need an ‘exit strategy’ for moving back to more breastfeeding. Once the baby is gaining weight well and for a good couple of weeks, we can look at reducing their reliance on formula. Milk removal makes more milk, so to increase your supply, you need to remove more milk from your body. This can be done in one of two ways:

Pump after feeds. You can double-pump after each feed for around 15–20 minutes. This milk can then be used instead of some of the formula that is necessary. You may feel that your breasts start to feel fuller after a few days, so you could try reducing the bottle volumes by your normal pump yield and keeping the baby slightly longer on the breast. You will find that pump yield goes down when you do this as the baby has taken that milk, but keep pumping and supply will increase further.

Cut back on supplements slowly. If you reduce the supplements at each feed by 5–10 ml and pop the baby back on the breast after their bottle, you should find that an additional 10 minutes or so of breastfeeding fills them up. In this case, we are using the baby as the 'pump', and after a short break from the breast while they had their bottle, they came back for dessert. After a few days, as supply increases, you may find that they no longer need this dessert. This would be a sign to decrease the bottle volume again by 5–10 ml. This method works best when the baby is a ‘good feeder’ and supply is the only challenge.

How do I combination feed?

Unii Expert Wendy Lever explains how to combination-feed your baby breastmilk and formula.