Once trained, a woman or couple usually can begin using calendar-based methods at any time. Give clients who cannot start immediately another method to use until they can start. 

Explaining How to Use Calendar -Based Methods

Standard Days Method

Important: a woman can use the Standard Days Method if most of her menstrual cycles are 26 to 32 days long. If she has more than 2 longer or shorter cycles within a year, the Standard Days Method will be less effective and she may want to choose another method.

Keep track of the days of the menstrual cycle

A woman keeps track of the days of her menstrual cycle, counting the first day of monthly bleeding as day 1. 

Avoid unprotected sex on days 8–19

Days 8 through 19 of every cycle are considered fertile days for all users of the Standard Days Method.

The couple avoids vaginal sex or uses condoms or a diaphragm during days 8 through 19. They can also use withdrawal or spermicides, but these are less effective.

The couple can have unprotected sex on all the other days of the cycle—days 1 through 7 at the beginning of the cycle and from day 20 until her next monthly bleeding begins.

Use memory aids if needed

The couple can use CycleBeads, a color-coded string of beads that indicates fertile and nonfertile days of a cycle, or they can mark a calendar or use some other memory aid.

Each bead represents a day of the menstrual cycle.

1. On day 1—the first day of monthly bleeding—move the rubber ring to the red bead.

2. The next day move the ring to the next bead. Do this every day, even bleeding days.

3. White bead days are days when the woman can become pregnant. She should avoid unprotected sex.

4. Brown bead days are days when pregnancy is unlikely and she can have unprotected sex.

5. If monthly bleeding begins again before reaching the dark brown bead, her menstrual cycle is shorter than 26 days.

6. If monthly bleeding does not begin before reaching the last brown bead, her menstrual cycle is longer than 32 days.

Calendar Rhythm Method

Keep track of the days of the menstrual cycle

Before relying on this method, a woman records the number of days in each menstrual cycle for at least 6 months. The first day of monthly bleeding is always counted as day 1. 

Estimate the fertile time

The woman subtracts 18 from the length of her shortest recorded cycle. This tells her the estimated first day of her fertile time. Then she subtracts 11 days from the length of her longest recorded cycle. This tells her the estimated last day of her fertile time.

Avoid unprotected sex during fertile time

The couple avoids vaginal sex, or uses condoms or a diaphragm, during the fertile time. They can also use withdrawal or spermicides, but these are less effective.

Update calculations monthly

She updates these calculations each month, always using the 6 most recent cycles.

Example:

– If the shortest of her last 6 cycles was 27 days, 27 – 18 = 9. She starts avoiding unprotected sex on day 9.

– If the longest of her last 6 cycles was 31 days, 31 – 11 = 20. She can have unprotected sex again on day 21.

– Thus, she must avoid unprotected sex from day 9 through day 20 of her cycle. 

If last cycles were 27-31 days, avoid sex or use another method on days 9-20.