Fertility Awareness Methods
(Updated December 2009, also available in Spanish)
What are fertility awareness methods?
When you use fertility awareness methods, you track when you are "fertile" or most likely to get pregnant. If you avoid having unprotected sex while you are fertile, you are less likely to get pregnant. There is more than one approach to determine when in your menstrual cycle you are fertile.
How effective are these methods?
If always used correctly, 3-5 out of 100 women who use these methods will get pregnant each year. If not always used correctly, 12-25 out of 100 women who use these methods will get pregnant each year.
How does it work?
You can use fertility awareness methods by keeping sperm out of your vagina on the days you are fertile. You are most fertile around the day your ovary releases an egg.
There are several ways to predict when you are likely to ovulate (release an egg). Your body changes in small ways around this time. If you track one or more of these changes, you can get an idea of when you are fertile.
- Temperature Method — Take your temperature with a special thermometer in the morning every day before you get out of bed. Your temperature rises by about 0.4°F around the time you release an egg.
- Cervical Mucus Method — The amount and texture of cervical mucus changes around the time your ovary releases an egg. Each day, check the changes in your cervical mucus. You can figure out when you ovulate based on these changes. A simpler approach, the TwoDay Method, only monitors the presence or absence of cervical mucus.
- Calendar Method (sometimes referred to as the rhythm method) — Chart your cycles on a calendar. Keep track of your fertile days.
- Standard Days Method — identifies a fixed fertile window in the cycle, days 8 to 19 every month for women with regular periods that come every 26 to 32 days. If you have your period monthly, your cycles are in this range.
When you are fertile, you have two options to prevent pregnancy:
- Do not have vaginal sex
- Use a barrier method like condoms
If you have unprotected sex on a day that you may be fertile, you should take emergency contraception as soon as possible within five days.
What are the benefits of using these methods?
- Fertility awareness methods are free or involve a small cost for tracking materials.
- Once you know how to use them, these methods are always available.
- If you decide you want to become pregnant, you can use one of these methods to know which days you are most likely to become pregnant.
What are the downsides of using these methods?
- Fertility awareness methods do not protect against sexually transmitted infections (STIs).
- You must be aware of your cycle and fertile days to know when to have or avoid unprotected sex.
- Fertility awareness methods are less effective at preventing pregnancy than some other birth control methods.
- Some women don't have regular periods. The calendar-based methods might not work for these women. Methods based on symptoms do not require having regular periods.
- Both partners must agree to use one of these methods. They have to agree to abstain from vaginal sex or use a barrier method during fertile days.
Where can I get more information?
For more information on fertility awareness methods, talk to your health care provider. For detailed instructions on practicing fertility awareness, see: