Glass containers are a good choice for long-term storage of breast milk. Glass bottles and jars are stronger than plastic breast milk storage bags, and since they can be washed and reused, they're also more environmentally friendly. However, glass containers can be dangerous: they're more likely to break and shatter than hard plastic storage containers or breast milk storage trays.
If you're planning to freeze breast milk in glass containers, be aware that not all glass is freezer-safe. Do not put regular glass baby bottles, baby food jars, or any other glass container into your freezer unless it's designed to withstand freezing temperatures. Even freezer-safe glass can break when exposed to rapidly changing temperatures, so it's important to defrost glass containers very slowly.
Make sure you do not fill glass bottles all the way to the top. Breast milk expands during the freezing process and could cause the glass to burst. Fill the bottle 2/3 or 3/4 of the way up to allow for expansion, then seal the bottle with an airtight cap to help protect the milk from contamination and odors during storage.
Using glass containers to store your breast milk has advantages and disadvantages. Below are the pros and cons.
- Glass containers are environmentally friendly.
- They are reusable.
- They are strong and less likely to leak and spill compared to plastic storage bags.
- Glass provides good protection against contamination.
- Glass can be dangerous if it breaks or shatters.
- Glass containers are not disposable. They need to be washed after each use.
- Glass containers take up more room in the refrigerator or freezer compared to storage bags.
- Glass must be defrosted slowly.
The glass storage containers below are freezer-safe and specifically designed for the storage of food.
Lifefactory glass baby bottles are available in 4-ounce (120 ml) and 9-ounce sizes (250 ml). They're made from toxin-free, thermal shock-resistant glass, so you can use the same bottle to pump, freeze, warm and feed your baby. These dishwasher safe bottles are covered with a silicone sleeve which provides a better grip and helps protect the bottle from breaking should it fall. Each bottle comes with a nipple, but you can purchase an additional solid cap for freezing and storing breast milk.
2. Wean Green
Wean Green's tempered glass food storage containers are durable and safe to use in the freezer. They're Bisphenol A (BPA)-, phthalate-, and PVC-free, with colorful non-toxic lids that snap on to provide a secure, airtight seal. Available in 4-ounce (120 ml) cubes, 5.1-ounce (150 ml) tubs, 5.6- ounce (165 ml) bowls, 7-ounce (210 ml) snack cubes, and 16.5-ounce (490 ml) lunch cubes, these eco-friendly containers are also dishwasher-safe for easy cleaning.
Ball and Kerr make 4-ounce and 8-ounce glass-preserving jars that are freezer-safe. Instead of a wide mouth, these jars have a regular-sized mouth which makes it easier to pour liquids and soft foods to and from the jars. They come with a two-piece canning lid; however, a plastic storage cap is available (sold separately) and recommended for freezer storage. Ball and Kerr jars are high quality, and once you no longer need them for your baby, there are so many other creative uses for these jars.
Lawrence, Ruth A., MD, Lawrence, Robert M., MD. Breastfeeding A Guide For The Medical Profession Sixth Edition. Mosby. Philadelphia. 2005.