Combo feeding breast and formula without losing your supply, one feed at a time

Combo feeding breast and formula works best when you change one feed at a time. Your body makes milk to match what is taken out, so every nursing session that becomes a bottle of formula tells it to make a little less. To keep your supply, pump at the time of the feed you replaced. To let it ease down gently, swap feeds slowly and skip the pump.

What decides whether combo feeding affects your supply?

What decides it is how often milk leaves your breasts, not how much formula your baby drinks. Milk supply runs on demand. Nurse or pump often and your body keeps making milk. Leave long gaps and it slows.

So two families can give the same amount of formula and end up in very different places. One replaces a nursing session and pumps at that time. The other replaces it and does nothing. The first keeps her supply. The second has told her body that feed is gone.

Three things also matter:

• How old your baby is. In the first weeks, supply is still settling, so a skipped session counts for more.

• How fast you change. One swap every few days gives your body time to adjust. Several at once can leave you engorged one week and low the next.

• How well your baby nurses. A good latch empties the breast better than a sleepy, shallow one. If you are not sure about latch, the guide to what is normal in the first days of breastfeeding is a good place to start.

Which feed should be the first one to become a bottle?

Swap the feed where you have the least milk, or the one that is hardest to be there for. For many families that is the feed where the breasts feel least full, or a feed that falls during work or an appointment.

A simple rule to decide:

• If you want to keep as much milk as you can, swap a feed you can pump around easily, and keep the first feed of the morning at the breast.

• If someone else needs to take one feed so you can sleep, swap the feed that falls in your longest stretch of sleep, and pump before bed instead.

• If your baby needs extra milk because of slow weight gain, follow the plan your pediatrician gives you. That plan comes first.

Keep the same feed as the bottle each day. A bottle that moves around the clock is harder for your body to plan for.

If your baby refuses the bottle at first, let another adult offer it while you are out of the room. Babies often expect the breast when they can smell you.

Do you need to pump when a nursing session is skipped?

Yes, if you want to keep your supply. No, if you are happy for it to go down. Both are fine choices.

Pumping at the time of the skipped feed tells your body the milk is still needed. The American Academy of Pediatrics' advice on low breast milk supply also says that when you are supplementing with formula, you should offer breast milk first and add formula after if your baby needs it. That way your baby gets all the milk you have, and none of it sits in the fridge waiting.

If you are choosing to let supply go down, still pump a little if your breasts feel very full. Take out just enough to feel comfortable. That eases the pressure without asking your body for more.

What does a three week move to combo feeding look like for one family?

Here is one example family. Their baby is six weeks old, breastfeeding well, and gaining weight. The mom is going back to work part time and wants to keep breastfeeding morning and night. This is an example, not a prescription, and your own plan may look different.

Week one: one bottle of formula, one pump

• The swap. The late evening feed becomes a bottle of formula, given by her partner.

• The pump. She pumps at the same time, while her partner feeds. The milk goes in the freezer for work days.

• What they watch. Her baby's wet diapers stay the same. Her breasts feel full but not sore in the morning.

Week two: a second feed moves

• The swap. A midday feed becomes a bottle too. On work days this one would be missed anyway.

• The pump. She pumps at midday on work days. On days at home, she nurses at midday instead of pumping.

• What they watch. One morning she feels a tender spot on one side. She nurses on that side first for the next few feeds and it settles. Her baby's diapers and mood stay the same.

Week three: settling the pattern

• The swap. No new swap. They keep two bottle feeds a day and let the routine set.

• The pump. She keeps the midday pump on work days and drops the late evening pump on two nights to see what happens. Morning feeds still feel full, so they keep it that way.

• What they watch. Weight at the next checkup is on track, and her baby still nurses happily in the morning and at bedtime.

What made it work was the order. One feed at a time, a pump where a session was missed, and a pause before changing anything else.

How can you tell supply is dropping, and what helps it recover?

The best sign is your baby, not the pump. Pump output goes up and down from day to day and is a poor measure on its own.

Watch for these:

• Fewer wet diapers than usual for your baby.

• Your baby seems hungry right after nursing, or nursing sessions get much shorter or much longer.

• Slower weight gain at a checkup.

• Your breasts stop feeling full before the feeds you are keeping.

What helps:

• Add a session back. Nurse or pump at the time of the feed you swapped most recently.

• Nurse first, bottle second. Offer the breast before any formula, as the AAP advises above.

• Check the pump. The AAP lists checking your breast pump among its steps for low supply. A pump that is not working well takes out less milk than your baby would.

• See your baby's provider. They will check growth, which is the clearest answer to whether your baby is getting enough.

When is it worth talking to a lactation consultant?

Talk to one early rather than late. A good time is before you start combo feeding, so the plan fits your baby and your goals.

Also reach out if:

• Nursing hurts, or your nipples are cracked or bleeding.

• Your baby's weight gain is slow or your pediatrician is worried.

• You want to build your supply back up.

• You keep getting clogged ducts.

HelianWell's experts include a maternal and child health expert whose background is lactation services in a hospital, and members can bring these questions to her.

Combo feeding FAQ

Can breast milk and formula go in the same bottle?

You can, but it is usually better to give them separately. Offer breast milk first, then formula if your baby still wants more. If your baby does not finish a mixed bottle, the breast milk in it is thrown away with the formula. Never use breast milk in place of water when you make up powdered formula.

Will combo feeding change your baby's poop?

Often, yes. Once formula is part of the day, poop is usually thicker, can smell stronger and may change color. Call your pediatrician if poop is hard and dry, has blood in it, or is white or very pale.

How do you avoid a clogged duct when dropping a feed?

Drop feeds slowly and keep milk moving. Cleveland Clinic's guide to clogged milk ducts names skipped feeds and changes to the feeding schedule as common causes. If one side feels full and tender, pump or nurse just enough to feel comfortable. Call your doctor if you get a fever, chills or a red, painful patch, because that can be mastitis.

Is it possible to go back to more breastfeeding later?

Often it is. The AAP's guide to relactation says it is sometimes possible to build supply again by nursing often and using a good pump. It also says it can take weeks, and that your baby's weight needs watching while you do it. It is easier with help from a lactation consultant or a doctor with breastfeeding expertise.

When to call your baby's doctor

Call your pediatrician if your baby has fewer wet diapers, seems hungry all the time, is not gaining weight, or is unusually sleepy and hard to feed. Call your own doctor if you have a fever or a painful red area on your breast. This article is general information and does not replace advice from your own pediatrician or lactation consultant.

Feeding support from people who know

If your baby has started solids too, the guide to how much milk a baby needs after starting solids picks up where this one ends. For the earliest days, see your first week home with a newborn.

HelianWell membership plans include feeding support from its named experts. See the plans in the pricing section of the HelianWell homepage.

Photo by Kedibone Isaac Makhumisane on Unsplash

Photo by Barney Goodman on Unsplash