I'd love to know what proportion of SAHMs are in that position because of solely wanting to further their husband's career, as opposed to, say, believing it's in the child's best interest to have a parental figure at home with them in their early years...
Probably much more likely that women either want to stay at home with their children, or that it doesn't make financial sense to return to work.
Luckily I was able to return to my old job after 3.5 years off with DD and am currently doing the same for my DS.
To suggest I'm unfeminist because I am 'putting my husband's career first' (which might be a positive side effect but was certainly not even one consideration in my decision to be a SAHM) and shows a poor understanding or value of the role of parenting young children.