Adding Breast Milk to a Formula Feeding Routine
For most healthy term infants, formula is the standard and complete alternative when breastfeeding is not possible. Some parents who are primarily or exclusively formula feeding want to introduce some breast milk — because a small amount becomes available, or because they want their baby to receive components present in human milk. This page covers how to approach this practically.
Why some parents introduce breast milk alongside formula
Breast milk and standard formula differ in composition. Some parents choose to introduce any available breast milk for this reason, particularly in the early months. The decision is a personal one — there is no established minimum amount with guaranteed effects. Discuss the practicalities with a lactation consultant or health visitor if you are considering this.
If you have some capacity to produce breast milk
Even parents who have been primarily formula feeding may be able to establish or maintain a small amount of milk production through expressing. This is not always possible — it depends on whether breastfeeding was established at all, how much time has passed, and individual factors. A lactation consultant can assess whether re-establishing or increasing supply is feasible.
Donor milk
For parents who cannot produce breast milk, pasteurised donor human milk is another route.
Formal milk banks (operated through hospitals in the UK, US, and many other countries) screen donors, pasteurise donated milk to established safety protocols, and supply primarily to preterm or medically vulnerable infants. This is the safest source of donor milk.
Informal donor networks (private arrangements or online sharing) are a different category. Donated milk from informal sources has not been screened or pasteurised and may carry risks including infectious disease transmission. If you are considering informal donor milk, discuss the risks with your healthcare provider before use.
How to integrate breast milk practically
If you have expressed breast milk and are primarily formula feeding: give breast milk first at relevant feeds, then offer formula if more is needed. This ensures the breast milk is not wasted if the feed is smaller than usual. Store expressed breast milk in the back of the refrigerator (not the door) and follow your national guidance on how long it keeps chilled or frozen.
Do not add breast milk to prepared formula in the same bottle as standard practice — if the baby does not finish, you will discard breast milk. Offer them separately where possible.
Storing and handling expressed breast milk
Expressed breast milk can be stored in a sterilised container at the back of the refrigerator (not the door) or frozen, for the times given in your national guidance. Defrost frozen milk in the fridge overnight or under warm running water — never in a microwave. Do not refreeze thawed breast milk.
