Yeah, but setting off a pregnancy test might be possible if Kei is taking hormones.
Premarin, one of the common forms of pharmaceutical estrogen Kei might be taking, is refined from PREgnant MARe urINe, after all. There might be something in there that would react with a pregnancy test strip.
Look forward to this, and other lectures in:
Moyashimon II: We'll brew your endocrine system!