Baby boy drinking milk from bottle

When To Switch Nipple Flow & Size, And How To Do It

The stress of being a new mom and making a multitude of decisions that feel like life or death for your baby can feel more than overwhelming. There are a lot of things to think about with a new baby, and baby bottle nipple sizes are probably at the back of your mind.

It’s something you need to consider and be prepared for, but it’s not nearly as stressful as it sounds right now.

Baby boy drinking milk from bottle

Your baby will tell you when it’s time to move, and then you simply have to follow the instructions on your package insert to change out the nipple for your baby.

If you’ve already thrown that away, don’t fear. We have a solution for that, too!

Bottle Brands and Nipple Flows

There is a wide range of bottle brands out there, and within each brand, you may find two or three different types of bottles. For each type of bottle, there are different nipples, and it all gets confusing very quickly.

However, each brand has a recommended age for each nipple stage. The slower flows are meant for younger babies, and they get progressively faster as your little one gets older. Your baby can handle more milk at a time once he eats more in one sitting.

There is no standard system that works across bottle brands, so you’ll have to refer to your specific brand for recommendations.

Every bottle brand has a different name for the stage of the flow, and it corresponds to a different age and readiness level.

If you found the brand that works best for you and your baby, your best bet is to stick to it as you increase the flow for your baby. Changing too many things too fast can upset or confuse your baby.

Here are some good general rules to get you started:

  • Babies younger than three months should use a slow flow nipple or newborn nipples
  • Babies between three and six months should use medium flows
  • Babies over six months can use fast flow nipples

When to Change Nipple Flow in Your Baby’s Bottle

There are different guidelines you should follow for changing the your baby bottle’s nipple, depending on what she eats and how you supplement.

There’s no hard and fast rule for how you should do it other than listening to your baby and looking for clues that she’s uncomfortable in one way or another.

When to Change the Nipple if Your Baby is Formula Fed

Use the age and flow guide for your bottle brand to get a good idea of what size nipple you should be using, and then pay attention to how your baby reacts to it.

If you’ve been formula feeding from birth, you likely started with the slower nipple flows and worked your way up.

It’s best practice to start at the slowest flow because slow flows are for younger babies. They don’t eat as much in one sitting, and they haven’t yet coordinated their swallowing, so they can’t handle fast flows yet.

Age isn’t always the best determining factor for nipple size because all babies are different. Pay attention to these signs to know if your baby is ready to move up:

  • Sucking too hard
  • Flattening the nipple
  • Getting visibly frustrated by squirming, pushing the bottle away, or kicking
  • Hitting the bottle
  • Taking more than thirty minutes or an hour to feed
  • Eating less than normal at feeding time and then being hungry again soon after

If you don’t notice any of these things and your baby seems fine, there’s no need to change the nipple flow. If you struggle with any of these things at feeding times, try moving up a size and see what happens. There’s nothing wrong with trial and error.

Also be aware of the signs that you should move back down a size. If your baby chokes, coughs, gags, or dribbles milk out of his cheeks, the flow is too fast.

Faster flowing nipples can also cause gas and digestive tract issues, so if your baby seems uncomfortable soon after he eats, you may need to move down a size or try a different brand that has a flow somewhere in the middle.

When to Change the Nipple if Your Baby is Breastfed

The bottle nipple flow size should always reflect what happens at the breast for a breastfed baby. Breastfed babies are used to working for their food because it comes out much slower at the breast than it does in a bottle.

Always start with the slowest flow your bottle brand has to offer. Most of the time, breastfeeding moms find that they never have to move up a size because breastmilk is thinner than formula, and travels through the nipple quickly anyway.

If you do move up to a faster flowing bottle nipple flow level, your baby gets used to the instant gratification and may refuse your breast, so be careful. Try to mimic natural breastfeeding as much as you can and be cautious not to overfeed.

Feed your baby in an upright position, change feeding positions halfway through the bottle, and pace the bottle feeding, so your little one doesn’t get used to an endless supply of milk. This will help caregivers other than you keep your baby on a routine and understand that bottle feeding is just like your breast.

There are times when you may find (as you breastfeed) that you need to move up a nipple size. It may be suitable to move up if your baby eats in five or ten minutes at your breast and is satisfied, but gets frustrated with the bottle and takes considerably longer to finish them.

Assess the flow and determine what works best for your baby. Don’t change it if it seems to be working, but don’t let your baby get frustrated with eating if it seems she is having a hard time with the bottle.

If you’ve been exclusively breastfeeding, the switch to bottle feeding can be tricky. Try buying a bottle brand that mimics the natural shape of your breast, whatever that may be. It makes the transition a whole lot easier.

Keep in mind that at first, your baby may be frustrated or uncomfortable with the silicone feeling. Don’t blame the nipple flow rates right away. Keep trying and if he still doesn’t get the hang of it, cautiously move up a nipple size to see if that solves it.

What Size Nipple to Use if You’re Exclusively Pumping

If you are exclusively pumping, you’ll find that many of the same rules apply here as they do if you’re breastfeeding.

It’s easy to overfeed a baby when bottle feeding, so start slow. Babies digest breast milk more quickly than they do formula, so you want to establish good habits when bottle feeding with breast milk.

Feed your baby on demand, but follow paced feeding practices. Use slower flowing nipples to mimic natural breastfeeding.

Nursing sessions usually take about fifteen or twenty minutes, so plan on your feedings taking the same amount of time. Don’t rush your baby. Allow him plenty of time to finish his food at his pace.

Other Things to Consider

If your baby is generally unhappy or uncomfortable with the flow of the nipples you’re using, go up a size to see if the flow was too slow. If your baby doesn’t seem to respond well to the faster flow, you can go back down, or consider other factors at play.

You can try a different bottle brand that has a different nipple shape, texture, or length.

There are also different venting systems, different styles of bottle, and different nipple or bottle angles.

You may also find that a bottle with anti-colic properties works better to reduce gas or other tummy troubles.

You can even get special nipples that are designed to be used when you start mixing cereal into your baby’s bottles.

Also, consider that the problem may not be the bottle at all. As babies grow, they go through phases.

Teething, growth spurts, and developing interests may mean they’re getting more and more distracted. Medical issues can affect appetite as well, so if your baby has a cold, he may struggle to eat.

The temperature of the milk may also be confusing to your baby. If you go from breastfeeding to bottle feeding, make sure you adjust the temperature of the breast milk or formula to room temperature or a bit warmer.

A bottle warmer might come in very handy here. If it’s too hot or too cold, your baby may not like the change.

The size and material of the bottle also affect the flow, so if you struggle with flow issues, try increasing or decreasing the size of the bottle.

Different bottle sizes, and therefore different volumes of liquid inside, apply different amounts and types of pressure on the nipple.

Different bottle and nipple materials have different air flow issues and will give your baby a different feeding experience. If you find that you can quite get the nipple flow on bottles just right, try something else to see if that helps.

Introducing Other Liquids

Check with your doctor before introducing juice or introducing water.

When your baby is ready, you may choose to introduce other liquids in a sippy cup rather than a bottle, or you may decide to stick with what you know at first. Either way is fine, but it’s good to at least try transitioning to sippy cups for purposes like this.

If you choose to give your baby other types of liquid in a bottle, go back to the newborn size nipple and work your way up. Liquids like juice and water are thin and have a different texture than breast milk or formula. They flow through the nipple more quickly and may warrant a slower flow.

Follow the same rules for switching out nipple sizes. Watch for signs that your child is frustrated before going up a size, and ensure that your child doesn’t choke with faster nipples.

By the time your child is ready for you to introduce other liquids, they won’t be the primary source of his diet, so you don’t need to worry too much about how long it takes him to drink it all.

Drinking juice or water is entirely different. He won’t drink as much at a time, and he shouldn’t be drinking as much of it as he drinks enough of his milk anyways.

The Dangers of Changing Your Bottle Nipple Size

As we’ve already addressed, you may find that your baby is uncomfortable with the current nipple size. Using a nipple that’s too slow frustrates her and adds more stress to her little body when she’s hungry.

Using a flow that’s too slow means your baby isn’t getting the nutrients she needs. Moving up a size eliminates frustration for both you and them, and ensures that she eats what she needs to eat.

However, if the flow is too fast for them and it’s not time to change to something like that just yet, your baby can suffer from much more serious effects.

A flow that’s too fast poses a choking hazard and can impact digestion. A flow that’s too fast can cause your baby to struggle. Not only could she choke, but she could swallow too much air, leading to painful gas and other gut issues later.

It’s better to have a flow that’s too slow than too fast, but if you can’t seem to find a flow that works for you, you should try a different brand that has something in the middle. Trial and error may lead you to something that works even better than what you’re currently using.

Steps to Change the Bottle Nipple

Changing the nipple out on your bottles should be fairly straightforward.

Unscrew the top of the bottle from the reservoir and pop the nipple out of the ring. Insert the new nipple into the ring and screw it back onto the bottle.

Depending on the brand of bottle you use, you may have extra attachments to contend with, in which case we suggest you refer to the manufacturer’s directions for changing out your nipple and assembling it correctly.

Wrapping It Up

Using the correct nipple size makes feedings go more smoothly. They’ll be more enjoyable for you and your baby.

Nipple size depends on a lot of factors including your baby’s age and whether you’re breastfeeding or have a formula fed baby.

While formula-fed babies typically move up in size as they grow, age isn’t always the best indicator. Your baby will demonstrate readiness signs such as sucking harder, taking longer than normal to finish a bottle, hitting the bottle, or being hungry shortly after bottles he doesn’t finish.

Breastfed babies won’t typically move up in nipple size because the slowest flow nipple best resembles a mother’s breast during nursing. It prevents overfeeding and keeps them preferring your breast over a bottle.

While these are some good general guidelines, bottles and nipples aren’t a one size fits all solution. You need to figure out what works best for you and your baby. And if you haven’t already noticed, each of your babies will be different, too.

If everything seems to be going smoothly with your current nipple size, don’t change anything. But if you feel like you need to move up, do it slowly and pay attention to how your baby responds to see if it was the right move.

Don’t worry if all doesn’t go smoothly at first – trial and error & a bit of consistency is all it takes!

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