I'm O neg as well and had anti-D which as the others said you have twice during your pregnancy and if your baby is born with a positive blood type you have another injection after the birth (I think within 12 hours of giving birth). My DD is O+. Don't know what DH's blood type is but it's obviously some kind of positive type and that's where DD got the positive from I guess.

I find it all very interesting how it works. Like my mum is O+ and my dad is AB-. My sister is the exact same type as my dad but I got the O from mum and the negative from dad.