Is it okay to keep expressed breastmilk warm in a Thermos flask, and then decant it into the bottle?

[feelinginthedark]

My babysitter is asking. I'm thinking no, because the flask wouldn't be sterile, but can't find this specific advice anywhere. She doesn't want to faff with Thermos flasks and hot water etc when out and about as she's worried my 2 year old will hurt herself. Thanks!

How about using the tommee tippee travel Warner?

Warmer!

Same issue with the hot water spilling - the only TT one I can see is essentially a thermos for hot water with a bowl? I might try the Prince Lionheart one with the heat pack but it has terrible reviews on Amazon!

Breastmilk can be kept at room temp for up to 6 hours, it doesn't need re heating.

I would think no. 37 degrees is ideal bug breeding conditions (think of yogurt -it's made by holding the milk at 45 degrees for several hours while the bacteria multiplies).

Express and leave at room temp is OK.