So many straw men (or straw women) on here.
One of the central points of radical feminism is critiquing the underlying assumptions of patriarchy. And one of those underlying assumptions is that work is only real work if it's paid work, hence motherhood (which as we all know is incredibly hard and very real work, as well as very rewarding) isn't "real work" in the eyes of patriarchy. Radical feminism accepts that it is real work, very valuable work, and very female work (because it is women who gestate, birth and then feed babies). I have never seen a form of radical feminism which invisibilises or devalues motherhood, quite the reverse in fact.
In dismantling gender what radical feminism seeks to do is dismantle the idea that women are mothers because we're innately nurturing (and the related view that sets nurturing up in contrast to, and exclusive of, "masculine" virtues like rationality, decisiveness, detachment). Everyone can be nurturing, rational, decisive, detached, engaged, caring, empathetic... to varying degrees as personality, upbringing and circumstances dictate. Women are mothers because of biology - hopefully then nurturing, caring, empathetic mothers because it's in the nature of looking after a child that one ought to be (but also rational in order to make good decisions about them, determined, detached when you have to say to them "you're not ill, you're pretending to be ill to get out of school today...")
The idea that radical feminism is somehow against stay at home mothers because radical feminists say they want to dismantle gender (an oppressive set of sex stereotypes) is, frankly, a complete crock of shit and utter (and wilful) misrepresentation of radical feminism.