"It’s much more complicated than that, for males at least. It’s quite easy for two women, as the enchantments only need to hold for the duration of, erm, the procreating act. But for men it’s a longer-term project," Hermione had interjected, going on to explain how a potion regime was needed to stimulate hormone production, replicate the menstrual cycle, and so forth. Harry had blushed and stopped listening at the word menstruation, but he’d gotten the gist of it.