Fertility Awareness
Fertility awareness works by observing and recording your body’s different natural signs each day of your monthly cycle to work out when you are most fertile.

Quick Guide
Key Facts about Fertility Awareness
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 during this time.
Pros & cons
- Does not involve taking any hormones or other chemicals.
- Can be used to plan pregnancy as well as avoid pregnancy.
- You must be properly taught the indicators to make sure your contraception method is effective.
- You need to avoid sex or use another type of contraception (like condoms) if you have sex during fertile times.
- It does not protect you from STIs.
How It Works
Fertility awareness works by observing and recording your body’s different natural signs each day of your monthly cycle. The main signs 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.
A specialist teacher will show you how to record the signs and explain what you can tell from them.
Fertility awareness doesn’t mean ‘withdrawal’ (removing the penis before the man comes).
Pros & Cons
Pros
- Fertility awareness is natural family planning method.
- Does not involve taking any hormones or other chemicals or using physical devices.
- Can be used to plan pregnancy as well as avoid pregnancy.
- Can be up to 99% effective if used correctly.
Cons
- 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.
FAQs
How long are you fertile for?
A menstrual cycle, on average 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 makes fertility awareness 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.
You will need to be taught natural family planning by a specialist teacher and there can be a cost.
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.
Where do I go for more information?
You can talk with your nurse, midwife or doctor about fertility awareness. Natural Fertility NZ provides education on fertility awareness – click here to visit their website.
Page last updated: 23 January 2020. Reviewed for clinical accuracy.