Persons who can participate in the study

The following people can participate in the study:

• Between 18 and 35 years
• Living in the Netherlands and speaking and understanding the Dutch and/or English language
• No desire to become pregnant for the next 12 months
• Prepare to use mifepristone 50 mg once a week for one year as the only method of contraception
• The expectation to have unprotected sex at least once a month with a partner who has not been sterilized
• BMI less than 35
• Regular periods (every 21-35 days) without using hormonal contraception
• Use of the 'normal' pill, a hormone IUD or a hormone rod, which means no 'real' menstruation
• After using the injection, there must have been regular menstruation of between 21-35 days in the last 3 months