I went with glass for the first 6 months.
Unfortunately, it was impossible to find a daycare that would accept glass bottles. They wouldn't touch them due to risk of breakage.
We went with polypropylene after that.
Seriously? The baby bottle I had as a kid (27 years ago) was made of glass so thick I can't even begin to imagine what would break it.
It's survived two babies (me and my sister), countless hikes, seaside vacations, boilings, reboilings, and probably a fair share of being thrown every which way. We still use it sometimes because it's handy as a measuring cup and I wouldn't be surprised if it stays in the family for a few more decades.
For comparison, I don't think a single piece of the "camping proof unbreakable" dish set my parents bought when I was ten is still alive.
Most glass bottles (Lifefactory, AVENT, Boobunny) use borosilicate glass which is what they use for laboratory glassware partly because it is stronger than normal glass. Many of these brands also sell a silicone sleeve that protects the bottle from being dropped.
Interesting - the only 2 daycares I know well enough to know the policy (if you want to call it that), both accept glass - or rather whatever you bring in. Both expensive places in center Seattle. I didn't even know there was another option.
