Breast milk storage bags are pre-made, self-standing flexible pouches that parents fill and freeze at home. For a private-label or OEM program, the specification comes down to five decisions: an odorless, food-contact polyethylene (PE) film, a leak-proof double-track zipper and side seals, a printed volume scale, a write-on label area, and — if consumers transfer milk to bottles — a pour spout. This guide walks through each choice and the documents to request before you approve artwork.
What a breast milk storage bag is — and is not
A breast milk storage bag is a consumer-filled pouch for refrigerated or frozen breast milk. In a typical program the retail unit is the bag paired with a printed folding carton, not a loose bag sold in bulk.
It is not a medical device and it is not a sterile, aseptic or "medical-grade" product by default. High-standard hygiene production and a pre-sterilized option are both scoped per program and confirmed for the selected factory, material and production run. If your brand wants a "sterile" or "pre-sterilized" claim on the pack, the sterilization method and its documentation have to be confirmed before artwork — do not print that wording on a standard PE pouch without it.
The material question: odorless, food-contact PE film
The standard structure is food-grade, odorless PE film with a tasteless zipper. Polyethylene is chemically stable at freezer temperatures and does not add odor or taste, which is why it dominates this category.
BPA-free. BPA (bisphenol A) is a monomer used to make polycarbonate and epoxy resins, not polyethylene — so a PE pouch is BPA-free by chemistry. That chemistry does not remove your documentation job: get the film supplier's material statement for your exact structure before you print a "BPA-free" claim.
Food-contact documents. In the EU, food-contact packaging falls under the framework Regulation (EC) No 1935/2004, supported by a supplier Declaration of Compliance for the specific material and structure (EUR-Lex, Regulation (EC) No 1935/2004; European Commission, Food Contact Materials legislation). For US programs, confirm FDA food-contact status for the same structure. Compliance is verified per factory, material and production run, and the documentation is shared with the quote where applicable — never assume a "food-grade" label transfers to a new supplier or structure.
The features that stop "liquid gold" leaks
When parents complain about a storage bag, the failure is almost always a leak or a broken zipper. Specify these deliberately:
- Double-track zipper. Two closure tracks give a reclosure margin and reduce the chance of a partial seal in the freezer.
- Leak-proof side and bottom seals. Ask for a seal-strength test report on your exact structure as part of qualification.
- Printed volume scale (ml/oz). A graduated scale lets parents measure without a separate container.
- Write-on area. A matte patch for date and volume is standard.
- Pour spout. A wide pour-in and pour-out spout makes bottle transfer less likely to spill.
A useful reference for what buyers specify is a real brand feature sheet: Medela's Easy Pour bags describe a wide pour-in/out spout, oxygen-barrier film, flat freezing, self-standing design, and a write-on label (Medela, Easy Pour Breast Milk Storage Bags — Key Features).
Capacity and format options
Offer two or three capacities rather than one; most programs cover the common pump-session range.
| Capacity (ml) | Capacity (oz) | Typical use |
|---|---|---|
| 150 ml | 5 oz | Small feeds, early pumping sessions |
| 180 ml | 6 oz | Mid-range feeds |
| 210 ml | 7 oz | Standard full feed |
| 250 ml+ | 8 oz+ | Larger feeds, higher-volume producers |
A flat-freezing, self-standing pouch stores more compactly in a freezer drawer; a pour spout adds material cost and sealing complexity, so decide it against how your customers actually transfer milk.
Print and private-label packaging
Printing is gravure, which suits the fine volume-scale lines and brand artwork on a flexible pouch. The printed elements to lock down are the scale, logo, instructions, and any write-on area position.
The retail unit is usually the bag paired with a printed folding carton, so plan the pouch and carton artwork together. Pre-sterilized production is a program-level option; its method and documentation are confirmed for the selected factory, material and production run.
What to send in the RFQ
A complete request keeps quoting fast. Provide:
- Capacity in ml and oz, and how many sizes.
- Material confirmation — odorless food-contact PE (or the alternative structure you need).
- Closure — double-track zipper; confirm seal-strength test requirements.
- Pour spout — yes or no.
- Volume scale and write-on area — position and print.
- Pre-sterilized option — required or not; if required, the claim wording you intend to print.
- Retail unit — bag only, or bag plus folding carton.
- Target market — EU and/or US, so the food-contact document scope matches.
- Quantity — your planned run volume.
| Item | Why it matters |
|---|---|
| Odorless food-contact PE | Prevents taste/odor transfer and is the base food-contact claim |
| Double-track zipper + seal test | The main defense against freezer leaks |
| Volume scale + write-on area | Core usability buyers expect |
| Pour spout | Trade-off between spill-free transfer and cost/complexity |
| EU/US document scope | Determines the Declaration of Compliance and FDA review |
Food-contact documents for EU and US programs are covered in more depth in our food-contact packaging document pack guide. When you have your capacity, market and closure decided, send the spec through our RFQ form — a width, height and quantity plus the choices above is enough to start the quote.