Natural family planning works best when all 4 methods are used together. Calendar or rhythm and standard days methods work only if you have periods every 26 to 32 days.
- Calendar or rhythm: Chart your menstrual cycle for a few months with a calendar, online calculator, or smartphone app. Figure out which days of the month you’re fertile and avoid having sex during that time.
- Standard days: The day your period starts is day 1. Avoid unprotected sex on days 8 through 19.
- Cervical mucus: Check your cervical mucus every day and write the results on a chart. To check your mucus, put a clean finger into your vagina to gather mucus. Place the mucus between your finger and thumb, then spread them apart to see if the mucus stretches. A few days before you ovulate, your mucus will become clear and feel slippery, kind of like raw egg whites. Avoid unprotected sex when your mucus feels slippery and for 4 days afterward.
- Temperature: Take and record your temperature every morning when you wake up. After you release an egg, your temperature rises by 0.4ºF (0.2ºC) and remains high for 3 to 5 days. Avoid unprotected sex from when your period ends until 4 days after your temperature rises.