Got a question?

Use the Ask Brook 24/7 tool to answer your query or search FAQs

Find a service

Search for your nearest Brook sexual health service here

Fertility awareness methods

Fertility awareness methods (also known as natural family planning) involves working out when a woman is in the most fertile phase of her monthly cycle, and avoiding unprotected sex (sex without contraception) during this time.

Every woman is different and fertility awareness  needs to be thoroughly understood if it is to be effective.

Fertility awareness doesn’t mean ‘withdrawal’ (removing the penis before the man comes). You should only use fertility awareness if you have been taught by a specialist teacher, so you can use it effectively.

Fertility awareness will not protect you from sexually transmitted infections (STIs) the best way to protect yourself from STIs is to use a condom every time you have sex.

Some key facts are:

  • Fertility awareness works by carefully observing and recording your body's different natural signs on each day of your monthly cycle, to work out your fertile time – fertility awareness indicators is not the same as withdrawing
  • Fertility awareness takes dedication and must be taught by a specialist teacher
  • You need to avoid sex or use another type of contraception (like condoms) if you have sex during fertile times

How does fertility awareness work?

Fertility awareness works by observing and recording your body's different natural signs on each day of your monthly cycle. The main signs you have to look at are:

  • Recording your body temperature
  • Monitoring cervical secretions (cervical mucus)
  • Calculating how long your menstrual cycle lasts

Changes in these fertility indicators can help you to identify your fertile time. You can also use fertility monitoring devices which you can buy in a chemist.

A specialist teacher will show you how to record the signs and explain what you can tell from them. 


How do I find out about fertility awareness?

You will need to be taught natural family planning by a specialist teacher and there can be a cost. For further information visit: Fertility UK at www.fertilityuk.org.

There are phone apps and online systems however the reliability and effectiveness of using these is not known, you should always be taught fertility awareness methods by a specialist teacher.

How long are you fertile for?

A woman’s cycle is approximately 28 days (although this can be longer or shorter) and the fertile period lasts for around eight to nine days. This is because eggs can live for 24 hours (and there can sometimes be a second egg released after 24 hours) and sperm can also live inside the body for up to seven days, so if you had sex seven days before ovulation you may still become pregnant. 

What is good about fertility awareness?

  • Can be used to plan pregnancy as well as avoid pregnancy
  • Does not involve taking any hormones or other chemicals or using physical devices 

What do you have to watch out for with fertility awareness?

  • Doesn't protect against sexually transmitted infections (STIs)
  • You need to avoid sex or use another type of contraception (like condoms) if you have sex during fertile times
  • You must be properly taught the indicators to make sure your contraception method is effective
  • It can take a few cycles to learn and work out how to predict your fertile days
  • You need to keep daily records
  • Some things such as illness or stress can make results difficult to interpret
  • It demands a high level of commitment from both partners 
  • It can take longer to recognise your fertility indicators if you have an irregular cycle, or have stopped using hormonal contraception

How effective is it?

When you use several indicators together according to teaching and instructions, fertility awareness can be up to 99% effective, depending on which method is used. This means that two in every 100 women who practise fertility awareness methods will get pregnant each year.

If not used correctly it will be less effective (estimated around 75% effective because of mistakes).

What makes it less effective?

Fertility awareness must be properly taught. Then the instructions must be properly followed or it will be much less effective.

Recent use of hormonal contraception may affect fertility indicators until regular menstrual cycles have been established. Women should have a minimum of three complete cycles after stopping hormonal contraception. 

Other medication, for example pain relief, antihistamines and some antibiotics can also affect different fertility indicators.

Who can use fertility awareness?

Most women can use this method if they have sufficient commitment and can share the responsibility with their partner.

However for some women for whom pregnancy poses a significant risk relying on fertility indicators for the prevention of pregnancy is not recommended.

Using fertility awareness after having a baby

It can take longer to recognise your fertility indicators after having a baby and also during breastfeeding.

If you are breastfeeding, some women use a contraceptive method known as LAM (Lactational Amenorrhoea Method). It can be very effective in avoiding pregnancy. If breastfeeding is to be used as a contraceptive it is recommended that women must be:

  • Fully or nearly fully breastfeeding day and night (no other liquids given or only other liquids given infrequently in addition to breast feeds. No long intervals between feeds day or night
  • You have no periods (amenorrhoeic)
  • Less than six months since having your baby

Women should be advised that the risk of pregnancy is increased if the frequency of breast feeding decreases, menstruation returns or when it is greater than six months since having a baby.

Using fertility awareness after abortion or miscarriage

It can take longer to recognise your fertility indicators after an abortion or miscarriage.