19Tu ne t'approcheras point d'une femme pendant son impureté menstruelle, pour découvrir sa nudité.
According to regulations in the Cleanliness Code, a woman in her period of menstruation is ritually unclean (See commentary on Leviticus 12:2). It is clear that anyone who touches her during that time becomes ceremonial unclean as well.
19 Tu ne t'approcheras point d'une femme pendant son impureté menstruelle, pour découvrir sa nudité.