The funny thing about beauty contests is that the women participating must be very sexy and beautiful in a sensual way. Think of the bikini round: bikini, makeup and high heels. It is a way of seeing an almost naked body. Yet the rules of the competition aim at excluding any of the behaviors that might be associated with such sexiness.
Hence the contestants
can't be pregnant or go out partying or even be married (I think). They must be pristinely unused, like a brand new gift in a cellophane wrap with a big bow on it.