Breastfeeding provides unmatched nutrition, protective benefits, and a unique connection with your baby. Most babies receive everything they need from breast milk alone, but there are times when supplementation may be needed to support growth, comfort, or medical needs. Supplementation simply means giving your baby additional milk—either more expressed breast milk or infant formula—to help meet those needs. With the right guidance and support, supplementation of any type can be used thoughtfully while continuing to preserve and enjoy the many benefits of breastfeeding.

Why Breast Milk Comes First

The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding—meaning no other food or drink besides breast milk—for about the first 6 months of life. Exclusive breastfeeding is associated with the greatest protection against health concerns for both the baby and the mom. In healthy, full-term newborns, the Academy of Breastfeeding Medicine recommends against offering routine supplementation unless medically necessary.  

Signs That Breastfeeding is Going Well

Breastfeeding can feel uncertain in the early days, but there are several reassuring signs that your baby is getting enough milk. Breastfeeding is generally going well when you notice the following:

  • Your baby is feeding at least 8–12 times in 24 hours

  • Your baby is active and alert at the breast, with plenty of soft, audible swallows

  • There are lots of wet and dirty diapers each day

  • Newborn weight loss stays within the 5–10% range, with a return to birth weight by about 2 weeks of age

When Baby May Need More Milk

It’s very common for mothers to worry about milk supply or how much milk their baby is getting, especially during the first few months of life. Early, unsupported formula supplementation can undermine a mom’s confidence in her ability to breastfeed and provide enough breast milk to her infant. Offering additional milk—even just a few times per day—without increasing breast stimulation can also begin a cycle of low milk supply.

When supplementation is needed, initiating hand expression and pumping as soon as possible helps protect milk production and supports ongoing breastfeeding.

Reasons Supplementation May Be Recommended

Healthcare providers may recommend short-term or ongoing supplementation for a variety of reasons, often related to the baby’s needs, the mother’s milk supply, or both. These recommendations are made to support your baby’s health while breastfeeding support continues.

Infant-Related Reasons

  • Early Baby: Preterm or low birth weight infants are at greater risk for feeding challenges and may be more likely to need additional milk.

  • Hypoglycemia: Supplemental colostrum, donor milk, glucose gel, or formula may be needed in addition to breastfeeding if a baby is at high-risk for, or develops symptoms of, low blood sugar. 

  • Dehydration: Inadequate wet diapers or the presence of uric acid crystals (oftentimes look yellowish or reddish-brown) may indicate that a baby needs additional milk while the mother receives breastfeeding support.

  • Excessive Weight Loss: Weight loss greater than 10% on day 5 or later may indicate the need for supplementation. 

  • Diaper Output: Fewer than 6 wet and 4 dirty diapers per day by days 4-5 postpartum may signal the need for supplementing breast milk.

  • Jaundice: Excessive sleepiness, poor feeding, and yellowing of the skin may indicate the need for feeding evaluation and supplementation.

  • Metabolic Disorders: Medical conditions such as galactosemia, maple syrup urine disease, phenylketonuria may require protein, carbohydrate or fat supplementation. Breastfeeding is sometimes possible, but should be supervised and coordinated by your healthcare team.

Maternal-Related Reasons

  • Delayed Milk Production: Milk production that is delayed beyond days 3–5, along with signs of inadequate intake by the baby.

  • Breast Development: Abnormal breast shape or limited breast growth during pregnancy may be associated with decreased milk gland development.

  • Breast Anatomy or Surgery: Breast anatomy concerns or prior breast surgery may increase the risk of low milk supply.

  • Temporary Weaning or Separation: Necessary medication use (most medications are safe for breastfeeding mothers) or separation without expressed breast milk available may require temporary supplementation.

  • Severe Pain During Feedings: Persistent pain during feedings that does not improve with breastfeeding support. A temporary, or sometimes permanent shift to exclusive pumping may be an option that allows the baby to continue receiving your milk.

Why Milk Sometimes Takes Longer to "Come In"

For many mothers, milk volume typically increases within the first few days after birth. It’s common for milk volume to take a little longer to increase for some mothers—this is normal and usually temporary. When this increase happens later than expected—after days 3–5 postpartum—it’s called a delayed onset of lactogenesis II. This can make it harder for a baby to receive enough milk in the early days and may increase the need for temporary supplementation.

Common contributing factors include:

  • First-time breastfeeding, as the body is learning this process for the first time

  • Limited or delayed breast stimulation in the first 24 hours after birth, including fewer or shorter feedings

  • Cesarean birth, which can delay early skin-to-skin contact and feeding

  • Prolonged labor or significant blood loss during delivery

Hormonal and metabolic factors may also play a role:

  • Maternal obesity

  • Polycystic ovary syndrome (PCOS)

  • Diabetes or insulin resistance, including gestational diabetes

  • Pregnancy-induced hypertension or preeclampsia

Less common but important causes include:

  • Retained placental fragments, which can interfere with the hormonal signals needed for milk production

  • Advanced maternal age

When one or more of these factors are present, early lactation support—along with frequent feeding, hand expression, and pumping—can help encourage milk production and support breastfeeding while your milk supply increases.

Options for Supplementing Breast Milk

Being advised to supplement can feel confusing or even stressful, especially when families assume formula is the only option. With the right lactation support, most breastfeeding mothers and babies can use expressed or donor milk before considering formula. Sharing your preferences with your baby’s healthcare provider helps create a feeding plan that protects breastfeeding while supporting your baby’s growth and nutritional needs.

Expressed Breast Milk

Mother's own milk is always the first choice when extra milk is needed. Hand expression is a simple and effective tool that can help boost supply and provide peace of mind. You can use it to give extra colostrum or breast milk after regular feedings. Combining hand expression with pumping can help provide larger volumes of milk, increase production, and yield milk that is higher in fat and calories, which is especially beneficial for newborn growth.

Donor Breast Milk

If your own milk isn’t available, donor breast milk is the next best option. Donor milk provides many of the same benefits as mother’s milk and is generally preferable to formula, particularly for medically vulnerable infants. Pasteurized donor human milk from a milk bank is carefully screened and processed to ensure safety. Many hospitals can provide donor milk when it is needed or requested.

Infant Formula

If neither mother’s milk nor donor milk is available, appropriate amounts of cow’s milk-based infant formula should be used. For babies with jaundice, the Academy of Breastfeeding Medicine notes that hydrolyzed casein formulas may be considered, as research suggests that they can be more effective at lowering jaundice levels than standard formula.

When using formula, it’s important to match the amount to what a baby’s stomach can hold at that age. This prevents overfeeding and supports a balance between your baby’s intake and your growing breast milk supply.

Preparing Formula Safety

In the newborn period, ready-to-feed or liquid concentrate formulas are preferred because they are sterile and carry a lower risk of bacterial contamination. Powdered formula is not sterile and may contain bacteria that can be harmful, especially for newborns, preterm infants, or babies with certain medical conditions. If you are preparing powdered formula, always follow the manufacturer’s exact instructions.

If your baby is at higher risk of illness, consider taking these extra steps to prepare powdered formula:

  1. Boil the water needed for formula preparation.

  2. Allow the water to cool for no more than 5 minutes before adding it to the formula powder.

  3. Shake well to mix the formula, then let it cool to room temperature before feeding your baby.

Following these steps helps ensure your baby’s formula is safe while supporting their growth and nutrition.

Can Breast Milk and Formula Be Mixed?

Some parents wonder if it’s safe to include a combination of breast milk and formula in the same bottle. While there is limited information about mixing human milk and formula, there may be some advantages to feeding them separately.

Practical considerations:

Although mixing breast milk and baby formula is generally considered safe, it can be wasteful. If your baby doesn’t finish the entire bottle, the mixed feeding must be discarded after one hour because formula milk spoils more quickly than expressed breast milk. If you aren't 100% sure that your baby is going to finish the full bottle feed, it's better to be safe and offer the feedings separately.

Potential downsides:

One study found that mixing formula with previously frozen breast milk reduced lysozyme activity—a key protein that fights infection—by 41% to 74%. NICU studies with premature babies linked decreased anti-infective activity to an increase in harmful bacteria like E. coli. If your baby is premature or has a compromised immune system, it may be safer to offer breast milk first and then top off with any formula that is needed.

Ways to Supplement While Supporting Breastfeeding

When supplementary feedings are needed, the safest way to offer additional milk while protecting your breastfeeding goals is to use alternative feeding methods whenever possible. These methods allow your baby to receive the nutrition they need while staying familiar with breastfeeding.

Options Include

  • Supplemental Nursing System (SNS) at the breast

  • Cup feeding

  • Spoon or dropper feeding

  • Finger feeding

  • Syringe feeding

  • Paced bottle feeding with a slow-flow, gradually sloped nipple

Using these methods can help prevent flow preference, which sometimes occurs when bottle feeding is started early. If bottle feeding has already begun, a responsive or paced bottle feeding approach encourages your baby to feed at their own pace, prevents overfeeding, and helps maintain breastfeeding skills.

Support Makes a Difference

Needing to supplement—whether briefly or for longer than expected—does not mean breastfeeding has failed. Many mothers experience a mix of emotions when supplementation becomes part of their feeding plan, including guilt, disappointment, or worry about their milk supply. These feelings are common, and support can make a meaningful difference.

Research shows that women who receive guidance from lactation consultants are more likely to continue breastfeeding and feel more confident in their feeding choices. With the right support, supplementation can be used thoughtfully to meet your baby’s needs while protecting your milk supply and honoring your breastfeeding goals. You don’t have to navigate this alone.

Disclaimer: Our classes and accompanying materials are intended for general education purposes and should not replace medical advice. For personalized recommendations, please consult your healthcare provider and/or lactation consultant.