I'm not a breeder and I've never bred Hedgehogs. (although I have been doing a lot of research for it)
But I don't think there's a minimum weight for the female's because they can be all different sizes.
I believe it just depends on weather the Female is healthy and is at a healthy weight for that particular female.
Anyone please correct if any of this is wrong.
Again I'm NOT a breeder and have never bred Hedgehogs.