Natural family planning (fertility awareness)

Natural family planning involves identifying the phases of a woman's menstrual cycle when she is most fertile as well as those phases when she is less fertile and, therefore, less likely to become pregnant.

How reliable is natural family planning?

It may not be reliable as a form of contraception when used on its own, but it can be helpful for couples wishing to avoid pregnancy and for those actively planning a baby.

If a woman's cycle is irregular then natural family planning will be less reliable.
There is no method of natural family planning which protects against sexually transmitted infections.

How effective is it?

Natural family planning can be up to 98% effective if used consistently and correctly according to teaching and instruction on use of the method This means that for every 100 women using the method for a year up to two women will get pregnant.

It is less reliable if the method is not used according to instructions.

How does natural family planning work?

Natural family planning is based on a number of factors pertaining to a woman's eggs (ova) and a man's sperm:

woman normally release an egg (ovulate) 14 days before the next period.
in a normal regular 28 day menstrual cycle, counting the first day of the period as day one, ovulation will occur around day 14. The ovulation day in the cycle will differ depending on how short or long the menstrual cycle is for individual women.
the egg only survives 12-24 hours therefore once ovulation has occurred, fertilisation must happen within 24 hours
sperm can survive for up to seven days following intercourse

The fertile phase is the time in the cycle when a woman is most likely to become pregnant if she has unprotected sex. If a pregnancy is not planned intercourse should be avoided during this time or a reliable method of contraception should be used.

Accurately identifying predicted ovulation is the cornerstone of natural family planning. There are three main methods of calculating ovulation:
calendar method
temperature method
mucus test.

To use any of the above methods correctly women need to learn how to record fertility signals such as your body temperature and your cervical secretions to identify when it’s safer to have sex.

Natural family planning cannot be learned solely from a book, it requires a specialist teacher to teach and coach you on the method. Ask your local sexual health service or G P for details of your nearest natural family planning specialist

Added benefits

No physical side effects
The method can be used to plan a pregnancy as well as avoid pregnancy.


Using the method effectively requires commitment and understanding from both partners
It can take up to 3-6 menstrual cycles to learn the method effectively.
You are required to keep a daily record of your fertility signals
If you are not planning a pregnancy and want to have sex during your fertile time (this may last around eight days per month) you need to use another method of contraception such as a condom.

Useful link:

The Billings Ovulation Method of Natural Family Planning

Help Icon

I think I have an infection

Get infomation See More Icon