Calendar Method

What is it?

The calendar method is when a woman tracks the days of her menstrual cycle on a calendar, for several months, to identify her fertility period.

How does it work?

For this method, the woman determines the start of her fertility period by subtracting 20 days from her shortest menstrual cycle. To determine the end of the fertility period, she subtracts 10 days from her longest menstrual cycle.

Does it prevent sexually transmitted infections?

Remember that most birth control or contraceptive methods will not protect a person from sexually transmitted infections (STIs).  To reduce the risk of STIs, including HIV, use a condom with another method of contraception. This is referred to as dual protection.

To be effective, birth control must be used correctly and consistently. If you want to prevent pregnancy, choose a method that you and your partner will use every time you have intercourse.

Talk to your health-care provider or visit a sexual health clinic to find out what might work best for you and your partner.

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Last updated: 2023-07-25