Glass vs stainless steel baby bottles

Both glass and stainless steel avoid the main problem with plastic bottles: shaking hot water and formula in polypropylene. Glass lets you see the milk; steel is lighter and won't break. Either way, the teat is usually silicone.

Why move away from plastic bottles

A 2020 study found that preparing formula in polypropylene bottles, with hot water and shaking as usually recommended, released microplastics into the milk. Infants were estimated to be the most exposed group.

Glass

• Pros: you can see volume and cleanliness; no taste; easy to sterilise; long-lasting.
• Cons: heavier; can break (a silicone sleeve helps but adds silicone).

Stainless steel

• Pros: unbreakable; light; good for travel and older babies.
• Cons: you can't see how much is left; usually more expensive.

The teat problem

Almost all teats are silicone, which counts as plastic under our definition. Natural rubber teats exist; some babies take to them and some don't. Silicone is heat-stable and many parents are comfortable with it; it's a much smaller issue than the bottle itself.

See the full swap: plastic baby bottles → glass or steel, and our guide to preparing formula with less plastic.