Can you use maternity bras for breastfeeding? Or must I buy new nursing bras?

Nursing bras has this flap that opens up so that its much easier during nursing. This is especially helpful if you are nursing on the go outside. You can use a maternity bra if you really want to but you will need to push down the whole bra cup to expose your nipples, which isn't very discreet. I personally prefer using nursing bras as I like to nurse in public and I can nurse quickly with a nursing top and a nursing bra.