I don't have a daughter but when I was younger my mum bought them for me which I was happy with, it wasn't until I was mid teens I started to buy myself.

I had a lot of embarrassment discussing it with my mum, my friend at the time had a totally different more open discussion with her mum, they used to joke about those kind of things, I wish me and my mum could have been more open like they were.

I'd say don't show any embarrassment when talking about it just be 'matter of fact' about it and hopefully she'll take your lead.