Calendar (natural family planning) icon

Natural family planning 

  • 76% to 88% effective
  • Requires daily use
  • Partner must be committed
  • No hormones
  • No STI/STD protection
  • Free or low cost


What is it?
  • Natural family planning is when people keep track of their fertility and either avoid having sex when they’re fertile or use condoms or other nonhormonal birth control when they’re fertile. It’s also called fertility awareness and the rhythm method.

  • There are 4 different methods: calendar or rhythm, standard days, cervical mucus, and temperature (or symptothermal). 

  • It’s not recommended for people with a short, long, or irregular cycle.

  • It’s considered one of the least effective forms of birth control. 
  • Avoid having vaginal sex or use a condom during the 10 days a month when you’re most fertile, 5 days before ovulation and 5 days during ovulation. Normally, your ovaries release 1 egg into the fallopian tubes each menstrual cycle. 

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.
  • Natural family planning is free.

  • Supplies (like calendars and thermometers) are easy to get and inexpensive.

  • You don’t need medications or devices.
  • Natural family planning isn’t as effective as other birth control methods.

  • About 12 to 24 out of 100 couples who use natural family planning get pregnant each year.

  • It’s difficult to know exactly when your egg will be released. It may happen at a different time every month.

  • Sperm can live in your body for 5 days, so if you have sex and then ovulate 1 to 5 days later, sperm may fertilize your egg.

  • Both partners must be committed to this method. 

  • You’re not protected against sexually transmitted infections (STIs/STDs), including HIV.

  • It takes lots of dedication and time to learn and understand how to do natural family planning.


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