Justin Wolfers argues that when women write with men, they are normally not given the same credit:
The accumulation of these slights suggests that even the world’s best female economists are given second billing too often. And none of this is intended to impugn the motives of any economic commentator. Rather, I suspect that there’s a simple unconscious bias at work here. Close your eyes for a moment, and picture an economist. Odds are you pictured a man. (Chances are, he was also white, most likely middle-aged, and probably fairly confident.) This same reflex makes it easier to recall those who fit this pre-conceived idea of what an economist looks like.