Yes, Plan B can delay the period but the duration of the delay is uncertain and varies from woman to woman. Taking Plan B creates a condition of hormonal disturbance in your body. Plan B typically contains a huge amount of progesterone. It is a hormone that naturally occurs in a woman’s body when she is pregnant. Progesterone slows down the ovulation process or completely stops it. If you take Plan B, you'll be taking a high dosage of that hormone which tricks your body into the concept that it’s already pregnant which stops the process of ovulation, thereby, delaying the periods for time being.