Medical Eligibility Criteria for
Calendar-Based Methods

All women can use calendar-based methods. No medical conditions prevent the use of these methods, but some conditions can make them harder to use effectively.

Caution means that additional or special counseling may be needed to ensure correct use of the method.

Delay means that use of a particular fertility awareness method should be delayed until the condition is evaluated or corrected. Give the client another method to use until she can start the calendar-based method.


In the following situations use caution with calendar-based methods:

  • Menstrual cycles are irregular. (For example, menstrual cycle irregularities are common in young women in the first several years after their first monthly bleeding and in older women who are approaching menopause. Identifying the fertile time may be difficult.)

In the following situations delay starting calendar-based methods:

  • Recently gave birth or is breastfeeding (Delay until she has had at least 3 menstrual cycles and her cycles are regular again. For several months after regular cycles have returned, use with caution.)
  • Recently had an abortion or miscarriage (Delay until the start of her next monthly bleeding.)
  • Irregular vaginal bleeding. (Delay until cycles have become more regular.)

In the following situations delay or use caution with calendar-based methods:

  • Taking medicines that can make the menstrual cycle irregular (for example, certain antidepressants, thyroid medications, long-term use of certain antibiotics, or long-term use of any nonsteroidal anti-inflammatory drug, such as aspirin or ibuprofen).