Could it be the pill?

Yesterday I posted about recent research showing that women have a preference for men of their own race in speed dating situations. I was puzzling about a possible evolutionary explanation for this result when I remembered that I'd read about research showing that women who are pregnant or taking the pill (because taking the pill works by tricking the body into thinking you're already pregnant) prefer men who smell similar to themselves (see here and here for example). Could it simply be that the female subjects in the experiment were taking the pill and that this was causing them to prefer men that were perceived as being more similar (i.e. of the same race)?