The rhythm method, also called the calendar method or the calendar rhythm method, is a form of natural family planning.
To use the rhythm method, you track your menstrual history to predict when you'll ovulate. This helps you determine when you're most likely to conceive.
If you're hoping to get pregnant, you can use the rhythm method to determine the best days to have sex. Similarly, if you're hoping to avoid pregnancy, you can use the rhythm method to determine which days to avoid unprotected sex.
Using the rhythm method for birth control requires careful record keeping and diligence. If you don't want to conceive, you and your partner must avoid having sex or use a barrier method of contraception during your fertile days each month.