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Fertility awareness (natural family planning)

5-minute read

What is fertility awareness?

Fertility awareness is a form of contraception where you learn to recognise on which days of the month you are fertile and can therefore conceive a baby.

It's known by several different names, including natural family planning, the rhythm method, the symptothermal method, the ovulation method, periodic abstinence, the mucus method or the Billings method.

During your monthly menstrual cycle, you will not be able to get pregnant for about half of the month. It's possible to try to work out whether or not you are fertile by watching for signs of ovulation, including your body temperature or the amount of mucus in your vagina. If you don't have sex on these days, you reduce your chances of getting pregnant.

Fertility awareness only works as a method of contraception if you follow the instructions very carefully — and your partner agrees to follow them too. Since you can get pregnant for a few days before and after you ovulate, you need to be very careful not to have sex on these days.

What are the types of fertility awareness?

There are different ways to use fertility awareness to avoid getting pregnant:

Calendar or rhythm method

Most women ovulate 12 to 16 days before their period. If you have regular periods, you can work out, over several months, when you should avoid sex. Remember, you are fertile for the week before you ovulate and for a few days afterwards.

This method can be quite unreliable. It's not suitable for women who have irregular periods. You can find more information about how to do calendar-based methods at Family Planning NSW.

Temperature method

Your resting temperature rises slightly after you ovulate. This method involves taking your temperature with a special thermometer before you get up every day. You need to take it in your vagina, rectum or mouth. When your temperature has risen for 3 days in a row, you can have sex for the next few days.

This method isn't very accurate because your temperature can be affected if you sleep in, drink alcohol or are stressed. It also means you can only have sex for about 12 in every 28 days.

Cervical mucous method or Billings method

The mucus inside your vagina (cervical mucus) changes during the month. Right after your period your vagina may feel quite dry, then around the time of ovulation the mucus becomes clear and stretchy, like raw egg white. After you have ovulated, it becomes thicker and cloudier. You can use these changes to work out when you ovulate. You should not have sex until 3 dry days have passed.

This method isn't suitable if you have abnormal bleeding from your vagina, if you have inflammation in your cervix or vagina, or if you're taking some medicines, including antibiotics, antihistamines or thyroid medicines, which can change your cervical mucus. Getting sexually aroused or having semen in your vagina can make it harder to tell what your mucus is like.

Symptothermal method

You take your temperature in the morning and examine your cervical mucus at night to work out when it's safe to have sex. You can also watch for various symptoms that show you are ovulating. These include some pain like period pain, spotting and tender breasts. Combining these different methods makes fertility awareness more accurate.

Is fertility awareness suitable for anyone?

Fertility awareness is not suitable if:

  • you have just stopped using a hormonal method of contraception, like the pill
  • you have irregular periods
  • you are getting close to menopause
  • your partner doesn't fully cooperate

What are the advantages and disadvantages of fertility awareness?

The advantages of fertility awareness are that it's a natural form of contraception with no side effects. It can be a good choice for women who can't or don't want to use other methods of contraception for religious, cultural or health reasons.

For women who follow the methods correctly and who are motivated not to get pregnant, they can be reliable. They cost nothing and they mean you get to know your body better.

However, women who use fertility awareness are more likely to get pregnant than women who use other forms of contraception. It depends how strictly you follow the method. About 1 in every 4 women who use these methods will get pregnant.

It can take quite a lot of time and patience to get fertility awareness right and you need to follow instructions carefully. Even so, some women will always find it difficult to predict when they are ovulating.

Using fertility awareness methods does not protect you from sexually transmitted infections (STIs). You will need to use other forms of contraception, such as condoms, to protect against STIs.

Remember also that fertility awareness can be affected if you are ill, stressed, taking some medicines or having sex.

Resources and support

You can find more detail on fertility awareness from these websites:

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Last reviewed: May 2021


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