Yes, some fields have a lot more women than men. The thing is that men can choose a lot more freely (although it is true there is prejudice against men in some areas, like male nurses), while women are facing a lot of prejudice, sometimes very hardcore prejudice, like death and sexual threats (and you can find a lot of incidents well documented). Men need not worry about such things if they choose to engage in a female dominated field.

The main issue, I think, is not whether women opt more or less for CS, but rather that many many are compelled/driven to opt-out of it. Something is clearly wrong if they can't opt freely without suffering prejudice or without having to, as some say, "grow a thick skin".