How to Supplement Your Baby While Breastfeeding

A Well-Fed Newborn Baby Is:

  • Easy to wake and keep awake during feedings most of the time
  • Actively sucks and swallows (you should be able to hear the swallows)
  • Looks satisfied after nursing
  • Is content to feed every 2–3 hours (more frequent feeding can be normal during growth spurts, and for a few hours once a day, but for newborns it may show ineffective feedings)
  • Has moist lips and obvious saliva inside of mouth
  • Loses no more than 4% in the first 24 hours of life and 7% by 48 hours of life (for vaginally birthed babies); 5% and 8%, respectively, for cesarean-born babies). See the Newborn Weight Loss Tool to evaluate your baby's loss/gain; a well-fed baby is above the yellow line on the graph
  • Gains about an ounce/day (after Day 4)
  • Is back to birth weight by Day 10
  • Has 6–8 wet diapers a day, light or pale yellow urine
  • Has 3–5 dirty diapers a day (can be fewer than this depending on their age)
  • Softens your breasts after feeding

How much milk does my baby need?

Your baby’s needs will change rapidly in the first few days. Here are some suggested amounts of supplement to start with.* Depending on how much colostrum your baby is getting from breastfeeding, how much energy they have stored prior to birth, and how hungry/thirsty they are, they may take more or less. 

Day 1: 10–15 ml

Day 2: 15–30 ml

Day 3: 30–45 ml

Day 4: 45–60 ml

*Always  feed your baby until they show fullness cues (see video below).

Infant Milk Calculator




These are suggested amounts to start with; remember that every baby is different. When your milk comes in, usually supplementation after breastfeeding is no longer needed. If it is, give any expressed milk first, then formula if baby is still hungry. You may want to see a lactation consultant at this point, if you feel things are not going in the right direction, and read about the basic principles of milk production. The first two weeks are critical for establishing your milk supply, so any problems with breastfeeding should be addressed immediately.

Almost always, you can trust your baby to tell you when they are hungry and when they are full. The exception is if your newborn is too tired to eat. They do not have the calorie reserves to safely go longer than 4 hours without eating when they are that little (3 hours if premature/small). You should attempt to feed your newborn at least every 3 hours (8 times/day). 

How to feed your baby

First, watch for your baby's hunger cues. If your baby is too sleepy to eat and they need to, you can insert a finger with a drop of milk on it or a bottle nipple into their mouth. Stroke the roof of their mouth until they start sucking. Then you can begin feeding. Start with breastfeeding on both breasts before you supplement, so your body will get a strong signal to make milk. (Adding pumping afterwards will also help.)

Make sure your baby is latched on correctly

Babies who are latched on correctly will get more milk and not hurt your nipples. Learn more here.

Increasing the flow of milk from your breast while baby is breastfeeding

Note: When the speaker says the word “there,” that indicates the baby swallowing a big mouthful of milk (watch baby’s chin).​ See more videos here.

Source: International Breastfeeding Centre

Supplementing at the breast with expressed milk or formula

Is formula safe?

Infant formula is safe and nutritious. It is modeled after human milk, and although it does not contain antibodies, it still provides the appropriate calories, fluids, and nutrition that babies need. What about all the chemicals you may have heard of? Well, breast milk is made of chemicals too, as are apples and oranges. I suggest starting with a basic cow's milk based formula, ideally generic, which costs about 1/3 of the price of brand name and contains the same nutrients. 

Curved tip syringe at the breast

Here’s how to use a curved tip syringe (available at hospitals, pharmacies, and online) to give breastmilk or formula, while baby nurses. Your hospital may have different types of feeding syringes that will work also. First, your baby must be latched on. Slightly pull back their cheek a tiny bit, just enough so you can see the corner of their mouth. Insert the syringe about 1/3 to 1/2 of the way with the point towards their cheek. 

Make sure baby is still latched, then very gently push the plunger to release milk. It’s important that you can feel the baby pulling; if they’re not sucking, this will not work well. Slurping noises indicate baby is not fully latched; take baby off and relatch them, then insert the syringe again.

Sometimes babies will suck the milk out of the syringe themselves, in which case, let them—less work for you! Notice how the baby’s sucking pattern changes once the syringe is in her mouth—this is exactly what you will see when your milk comes in and your baby is swallowing gulps of milk.​ Tongue and lip ties are referred to in the video; learn more here.

Syringe and finger

The advantage of this method is that it allows you to collect and feed tiny amounts of colostrum. It should be noted that there is no proven advantage to using a finger over a bottle nipple; a bottle nipple is softer and more like a human nipple than a bony finger (see video below).

Supplemental nursing system

Like with a curved tip syringe, a supplemental nursing system allows you to slip a thin tube into the corner of your baby’s mouth, so they can get supplemental milk while nursing. This has the advantage of providing breast stimulation (if the baby has an effective latch and is pulling on mom’s nipple, not using the tube as a straw), while also getting their full feeding at the breast. This can be helpful when a baby is frustrated with a slow-flowing breast (slow flow often comes with low supply).

Bottle feeding a breastfed baby

Here is how to bottle feed your newborn responsively. Use a slow-flow newborn sized nipple with expressed breast milk or ready-to-feed formula. Make sure you first tickle baby's lips with the nipple and wait for them to open their mouth wide—just like you would with the breast—before putting the nipple in. If the baby is too sleepy for you to elicit hunger cues and they must eat (such as in the case of low blood sugar), you can just slip the nipple into their mouth; when the baby feels the nipple touch the roof of their mouth, their sucking reflex will be triggered. If it doesn’t work, try putting the nipple a little further in and give it a gentle wiggle. Letting baby taste a drop of colostrum or formula can sometimes help. 

Hold your baby in an upright position, with the bottle horizontal. Tip it up slightly so milk is filling the nipple.

Your baby’s position while bottle feeding is important. Babies held in an upright position while feeding have fewer respiratory and ear infections.

Do not waterboard your baby—let them control the flow, without gravity doing the work.

“Pacing” the feed by giving frequent breaks from milk flow is not necessary, and can be frustrating for the baby. Bottle feeding—like breastfeeding—should be a relaxed, enjoyable experience for the baby and parent. If your baby is eating too fast and appears uncomfortable (milk leaking around the lips, stressed facial expression, coughing or turning away from the bottle), give baby a break, and check that the nipple isn’t flowing too fast. If they appear frustrated, or the nipple collapses during sucking, it may be too slow. At the bottom of the page, I will discuss nipples and flow rates.

Make sure your baby latches well onto the bottle. Their mouth should be wide open and on the base of the nipple, not just the tip. Use a bottle that flows in a comfortable way, and ideally one that is similar to your nipple in "squishiness" and shape (when stretched out). 

If you only have a tiny amount of colostrum to put in the bottle, unscrew the nipple and just put it right in the nipple, so it doesn't get lost around the rim of the bottle.

Micromanaging the feeding is not necessary; your baby will not overeat when they can control the flow and you’re using upright positioning and watching their fullness cues as described in the video. (Note that occasional spit-up happens and does not mean you overfed your baby; their stomachs are just immature at this point in time.)

Always feed your baby until they show signs of being comfortably full

After you feed the milk, hold baby upright for a couple of minutes to see if they need to burp, then offer more by touching baby's lips. If your baby is still showing signs of interest in eating, continue feeding more. Stop when your baby shows fullness cues.

Note that once baby's saliva has touched the nipple, any milk left in the bottle after the feeding must be thrown out: within two hours for breastmilk, and one hour for formula. Here are the CDC guidelines for preparation and storage for breastmilk and formula.


(If you find the following information highly confusing and frustrating, I don’t blame you. I would suggest just picking a few and seeing which one your baby seems to like the best, and if possible, get a brand whose flow doesn’t vary much.)

Unfortunately the terms "slow flow," "natural," "like breastfeeding," etc., are not based on any standards and are essentially meaningless. For example, here is a chart showing flow rates of typical bottles. You can see that the Medela Calma flows very quickly, whereas the Philips Avent Natural First Flow is very slow:

Milk flow rate from bottle nipples

To make matters worse, as you can see in the chart below, nipple flow rates vary greatly even within the same type; for example, if you have several Philips Avent Natural First Flow nipple, chances are they each flow very differently. The Philips Avent Anti-colic 0m+ nipples all flowed at a pretty similar rate in this study. 

The best nipple to use long-term is the one that flows most similarly to the mother’s flow. Some mothers have a faster letdown than others. You can guesstimate how fast your letdown is by how quickly your baby is gulping, or how quickly you can pump out what’s in your breasts. There is a pretty wide variation in what is normal and fine for your baby. Don’t stress over this too much! Just pick one your baby likes and is hopefully not too expensive or hard to clean.