Medical theories that assume that marriage is the natural state for men and women, and that single women have no sexual activity, conclude that there is in single women "an imbalance between yin and yang," with illness being the result.
由於「男大當婚、女大當嫁」，這一類的醫療論述假設單身女性沒有性活動，因此會「陰陽失調」而發生病痛。