This page gives information on how natural family planning can help you to avoid pregnancy.
Fertility awareness involves being able to identify the signs and symptoms of fertility during the menstrual cycle so you can plan or avoid pregnancy.
Read this information to find out:
The menstrual cycle is the time from the first day of your period to the day before your next period starts. The average length of the menstrual cycle is around 28 days, although many women have longer or shorter cycles and this is normal. Regardless of how long or short the cycle is, ovulation (when the ovaries release an egg) will usually happen around 10–16 days before the start of the next period. During your menstrual cycle:
The menstrual cycle is controlled by your body’s natural hormones – estrogen and progesterone.
Natural family planning works by observing and recording your body’s different natural signs or fertility indicators on each day of your menstrual cycle. The main fertility indicators are:
Changes in these fertility indicators can help you to identify your fertile time. You can also use fertility monitoring devices (see How do I use fertility monitoring devices?).
The fertile time lasts for around 8–9 days of each menstrual cycle. This is because the egg lives for up to 24 hours. Occasionally, more than one egg is released at ovulation (within 24 hours of the first egg being released) and sperm can live inside a woman's body for up to seven days. This means that if you have sex as much as seven days before ovulation you may get pregnant.
How effective any contraceptive method is depends on how old you are, how often you have sex and whether you follow the instructions.
If 100 sexually active women don't use any contraception, 80 to 90 will become pregnant in a year.
If used according to teaching and instructions, natural family planning methods are up to 99 per cent effective, depending on which method is used. This means that up to one woman in 100 will get pregnant in a year.
If natural family planning methods are not used according to instructions, more women will get pregnant.
Natural family planning is more effective when taught by a specialist natural family planning teacher, and when more than one fertility indicator is used.
Some people choose to combine their fertility awareness knowledge with male or female condoms – this is sometimes known as fertility awareness combined methods. The effectiveness of this depends on how well you use male or female condoms.
Most women can use natural methods as long as they receive good instructions and support. They can be used at all stages of your reproductive life, whatever age you are. Natural family planning may not be a suitable method for women who do not have periods.
It may take longer to recognise your fertility indicators and to start to use natural family planning if you have irregular cycles, after stopping hormonal contraception, after having a baby, during breastfeeding, after an abortion or miscarriage, or when approaching the menopause.
Some natural methods rely on using only one of the fertility indicators. Other methods use two or more indicators, this is more effective.
© Copyright J Knight and C Pyper. Adapted from Fertility UK 2005.
The hormones estrogen and progesterone cause your body temperature to change throughout the menstrual cycle – it rises slightly after you have ovulated. You can chart these changes by recording your temperature each day to show you when the fertile time ends. Visit www.fertilityuk.org to download a fertility chart. You should use a special mercury fertility thermometer or digital thermometer which will show the small changes in temperature more easily. Ear or forehead thermometers are not accurate enough to use for natural family planning.
You need to take your temperature before you get out of bed or after you have had at least three hours rest. This is known as your basal body temperature (BBT) or waking temperature. This should be done at the same time each day and before you have anything to eat or drink.
The fertile time ends when you have recorded temperatures for three days in a row, which are higher than all the previous six days. The difference in temperature will be about 0.2 degrees Centigrade (0.4 degrees Fahrenheit).
Certain activities or events can alter your temperature readings and can make them less accurate. For example if you:
The temperature indicator on its own does not help you to find the start of your fertile time.
The amount of estrogen and progesterone varies in the menstrual cycle and this alters the quantity and type of cervical mucus. By monitoring the changes in your cervical secretions you can learn to identify the start and end of your fertile time.
The amount and quality of cervical secretions will vary from woman to woman and also from one cycle to the next.
Yes. Combining the temperature and cervical secretions indicators acts as a double check and increases the effectiveness of natural family planning.
The fertile time starts at the first sign of any cervical secretions and ends after the third high temperature has been recorded and all three high temperatures occur after the last day of having wet or clear, slippery secretions (the peak day).
The length of your cycles can help you to work out the start of your fertile time. Keep a record of the length of your last six cycles, then find your shortest cycle and subtract 20 days to find the first fertile day. Calculating your cycle length is not a reliable way of working out the end of your fertile time and should not be used on its own as a fertility indicator.
During your menstrual cycle your cervix changes in position and feels different. Around your fertile time the cervix will feel higher in the vagina, soft and slightly open. During your infertile time your cervix will feel low in the vagina, firmer to touch and closed. These changes are not reliable enough to be used on their own as a fertility indicator.
Some women may be aware of pain around ovulation or changes in the breasts, skin, mood or sex drive. These are the least reliable indicators of your fertile time.
You can buy a number of different fertility devices. They work by monitoring changes in temperature, urine or saliva. In the UK the main product available is Persona. This consists of a small handheld computerised monitor and a series of urine test sticks which measure hormonal changes. Persona interprets these changes and can predict the fertile and infertile times of your menstrual cycle.
If you use Persona according to the instructions, it is around 94 per cent effective. This means that at least six women in 100 will get pregnant in a year.
Computerised thermometers work by combining information about the length of your menstrual cycle and temperature. More research is needed about the effectiveness of these products.
Luteinising hormone (LH) dipstick tests or ovulation predictor kits are designed to be used by women planning a pregnancy. They are not effective as a natural family planning method.
Breastfeeding is also known as lactation. When used as a contraceptive method it can be very effective in avoiding pregnancy and is known as lactational amenorrhoea (LAM).
LAM can be up to 98 per cent effective in preventing pregnancy if all of the following conditions apply:
The risk of pregnancy increases if:
Once your baby is over six months old the risk of getting pregnant increases so, even if you don't have periods and are fully, or nearly fully, breastfeeding, you should use another contraceptive method.
Yes. Using hormonal emergency contraception will upset your normal hormone pattern and alter your fertility indicators. After using hormonal emergency contraception you should not rely on your natural family planning indicators for two complete menstrual cycles. This allows time for your cycle to return to normal and for your natural family planning indicators to be reliable.
You will need to find someone to teach you how to use natural family planning. General practice and contraception clinics do not often teach it so you may need to find your own teacher – some charge a fee. You can get further information from: