Before you can use the calendar method as birth control, you need to keep track of the length of your menstrual cycles for at least 6 periods. Hereâs how you do it:
- Mark the first day of your period (this is day 1).
-Then mark the first day of your next period.
- Count the total number of days between each cycle (the number of days between the first days of each period).
- You must chart at least 6 cycles, but charting a few more months is even better.
If all of your cycles are shorter than 27 days, the calendar method wonât be accurate for you. To predict the first fertile day (when you can get
pregnant) in your current cycle:
- Find the shortest cycle in your past record.
- Subtract 18 from the total number of days in that cycle.
- Count that number from day 1 of your current cycle, and mark that day with an X. (Include day 1 when you count.)
- The day marked X is your first fertile day.
To predict the last fertile day in your current cycle:
- Find the longest cycle in your record.
- Subtract 11 from the total number of days in that cycle.
- Count that number from day 1 (the first day of your period) of your current cycle, and mark that day with an X. (Include day 1 when you count.)
- The day marked X is your last fertile day.
The calendar method can only predict what are most likely to be safe and unsafe days, it canât tell you for sure exactly when youâre fertile. So itâs hard to use if your cycles are not always the same length, and you canât use it at all if all of your cycles are shorter than 27 days. The calendar method is most effective when you combine it with other fertility awareness methods, like the temperature and cervical mucus methods.
Next Steps
Follow the steps as advised