In the 1920s and 1930s, married women's hairstyle changed gradually from the bun to the modish perm. On the wedding day, the girl went to the barber's to have her hair permed, accompanied by her female friend or relative. After the perming, when she walked on the street, every one (no matter acquaintances or strangers) could understand that she would become a bride soon. In that period, the boundary betweenYisaoandYimeiwas still clear, so you would not make a mistake if you call someone according to her hairstyle.
Later on, unmarried teenage girls also had their hair permed, and someYisaowho had become mothers still plaited their hair, so it became hard to tell aYisaofrom aYimeiaccording to the hairstyle only.