Natural family planning

Page last reviewed: 13/07/2011

Natural family planning is a form of birth control where natural signs, such as body temperature, are used to identify when a woman is at her least and most fertile during each menstrual cycle.

It is possible to avoid pregnancy by only having sex during the woman's infertile periods.

There are two main methods of natural family planning. They are:

  • methods based on fertility awareness - which involve avoiding sex during fertile periods
  • the lactational amenorrhoea method - which can be used during the first six months after giving birth; you are unlikely to fall pregnant during this period providing you are breastfeeding fully and your periods have stopped  

See Natural family planning - how it works for more information.

How reliable is natural family planning?

As long as the instructions are followed correctly, the IFPA (Irish Family Planning Association www.ifpa.ie ) state that natural family planning methods are up to 99% effective at preventing pregnancy. This means that up to one woman in 100 will become pregnant in a year while using these methods.However, if a woman's menstrual cycle is irregular, natural family planning methods are less reliable.

Also, as natural family planning depends on making calculations or judgments about imprecise signs of fertility, many couples find them difficult to use. The methods rely on a woman knowing her body well.

Combining natural family planning with another form of birth control, such as a condom, is recommended for couples who want to avoid pregnancy at all costs.

One of the main advantages of natural family planning is that it does not involve the use of chemicals or hormones and therefore does not have any side effects.

See Natural family planning - advantages and disadvantages for more information about the pros and cons of this form of birth control.

Who can use natural family planning?

Most people who learn and fully understand natural family planning can use it effectively.

However, for some women, natural family planning may not be the most suitable method of contraception. Some women may not be able to use the lactational amenorrhoea method at all. See Natural family planning - cautions for more information.

How does natural family planning compare?

If used in accordance to teaching and instructions, natural family planning is as effective, or in some cases more effective, at preventing pregnancy than other methods of birth control.

Below is a list of the various forms of birth control and their effectiveness.

  • Natural family planning - 99% effective if used correctly (up to 1 in 100 women will become pregnant in a year)
  • Contraceptive vaginal ring - 99% effective if used correctly (less than 1 in 100 women will become pregnant in a year)
  • Contraceptive patch - over 99% effective if used correctly (less than 1 in 100 women will become pregnant in a year)
  • Combined pill - over 99% effective if used correctly (less than 1 in 100 will become pregnant in a year)
  • Progestogen-only pill - over 99% effective if used correctly (less than 1 in 100 will become pregnant in a year)
  • Male condoms - 98% effective if used correctly (2 in 100 women will become pregnant in a year)
  • Female condoms - 95% effective if used correctly (5 in 100 women will become pregnant in a year)
  • Diaphragms and caps - 92-96% effective if used correctly with a spermicide (4 to 8 women will become pregnant in a year)

Page last reviewed: 13/07/2011

Natural family planning methods fall into two main categories:

  • methods based on fertility awareness
  • the lactational amenorrhoea method

Methods based on fertility awareness

All fertility-awareness methods involve:

  • determining when ovulation occurs in your menstrual cycle (when an egg is released from your ovaries)
  • not having sex from seven days before ovulation until one to two days after ovulation, asthis eight-to-nine-day period is when you are fertile (see box, right).

You can predict the time of ovulation by monitoring one or more of the following:

  • the length of your menstrual cycle
  • changes in your body temperature
  • changes in your cervical secretions (coming out of your vagina)
  • changes in the hormone levels in your urine or saliva - measured usinga fertility monitoring device (see box, left) 

The fertility-awareness methods that use these natural signs are summarised below.

The calendar method

  • Record the first day of every period (day one of each menstrual cycle) for six months.
  • Work out the length of each menstrual cycle during those six months. This is the number of days from the first day of your period to the first day of your next period (normally about 28 days).
  • Take the length of your shortest cycle and the length of your longest cycle.
  • Subtract 18 days from the length of your shortest cycle - this is the first day of your fertile period.
  • Subtract 11 days from your longest cycle - this is the last day of your fertile period.
  • Do not have sex from the first day to the last day of your fertile period.

The temperature method

  • Every morning, take your temperature (using a thermometer) after waking, before you get out of bed. Try and take it the same time each morning. Keep a record of these readings.
  • After six readings, work out your average body temperature (add the measurements and divide by six).
  • When you take three temperatures in a row that are all higher than your average, ovulation has taken place.
  • From the third day of increased temperature (the third day after ovulation), you will have entered an infertile phase because it is unlikely that your egg will be fertilised. You will be protected against pregnancy from this time until your next fertile period.

However, various factors can upset your body temperature, such as illness or some medications. Speak to your GP or nurse for more advice on this method.

The mucus method

  • Every morning, use your finger to take a sample of the secretion coming out of your vagina.
  • Press the sample against your thumb and slowly separate your thumb and finger, to test the consistency.
  • If it seems clear and stringy, like egg white, you are about to ovulate.
  • You will enter an infertile phase from four days after this point (when there is no longer lots of clear mucus), which lasts until your next fertile period.

However, if you have recently had sex or are sexually aroused, the consistency of your secretion will be affected. A vaginal infection such as thrush will also affect your secretion. Therefore this is not a particularly effective method of contraception when used alone. For more information, speak to your GP or nurse.

General factors affecting your fertility signs

It may take longer to identify your fertility signs (such as temperature and cervical secretions) if:

  • you have irregular periods
  • you have recently stopped taking hormonal contraception
  • you have recently had a miscarriage or termination
  • you have recently given birth and/or are breastfeeding
  • you regularly travel through different time zones

Other factors that affect your body's natural signs include:

  • altering how and when you take your temperature
  • drinking alcohol
  • taking certain medication
  • being ill

For more information, see Natural family planning - cautions.

The lactational amenorrhoea method

The lactational amenorrhoea method can be used as a method of birth control if you have recently given birth.

It means taking advantage of the first six months after giving birth, during which time you will be unlikely to fall pregant, providing that:

  • your periods have completely stopped during this period
  • you are fully breastfeeding (because you produce hormones that suppress ovulation when you are breastfeeding)

The method is not effective for any longer than six months after the birth of your baby, as your fertility will have increased by then and other foods will be substituted for breast milk, so you will not be fully breastfeeding.

This method is not foolproof and is rarely recommended as a sole method of contraception.

Ovaries
Ovaries are the pair of reproductive organs that produce eggs and sex hormones in females.

Fertility monitoring devices

Fertility monitoring devices are computerised monitors that record changes in your body temperature or levels of hormones in your urine or saliva.

They can be bought from pharmacies and are effective if used precisely.

Fertility facts

  • A woman ovulates 10-16 days before the start of her next period.
  • Following ovulation, she is fertile for 24 hours.
  • However, as sperm can live inside the body for up to seven days after ejaculation, the actual fertile period is around eight or nine days.
  • If an egg (or occasionally, more than one egg) is released and sperm are present, fertilisation can occur.

Calendar method

If your shortest menstrual cycle is 26 days and your longest cycle is 33 days...

  • subtract 18 from your shortest cycle (26 days) = 8 days.
  • subtract 11 from your longest cycle (33 days) = 22 days.

Avoid having sex from day 8 to day 22 of your menstrual cycle.

Page last reviewed: 13/07/2011

Methods based on fertility awareness

The advantages of using fertility-awareness methods are:

  • Most women can use them, providing they are properly trained by a specialist in fertility awareness and keep accurate records.
  • You do not need any further help from a healthcare provider once you have learnt how to use them.
  • They can be used to avoid pregnancy or to become pregnant, according to your wishes.
  • They do not involve chemicals or physical products, so there are no adverse side effects.
  • They can help you recognise normal and abnormal vaginal secretions, so you are aware of any sexually transmitted infection.
  • They are acceptable to all faiths and cultures.
  • They are immediately reversible - as soon as you stop using the methods, you can get pregnant (unlike some hormonal methods, where your fertility can take a while to return).

The lactational amenorrhoea method

The advantages of using the lactational amenorrhoea method are:

  • It is effective for six months.
  • It can be used immediately after childbirth.
  • You do not have to avoid sex.
  • It does not involve chemicals or physical products, so there are no adverse side effects.

 

Useful Link

Page last reviewed: 13/07/2011

Methods based on fertility awareness

The disadvantages of using fertility-awareness methods are:

  • They rely heavily on your ability to accurately work out your fertile periods each month. If your signs are not correctly judged or calculated, the method has a high risk of failure.
  • They are not suitable for women with irregular periods.
  • You have to avoid sex for eight to 16 days in each menstrual cycle. Some couples find this difficult.
  • They demand a high level of organisation, and it may take as long as six months to discover your fertile period. During this time, you must keep a diary of your body signs every day to ensure that your records are accurate.
  • Your body signs may be difficult to interpret if you are tired, stressed or ill. Such factors may alter your signs to the extent that the contraceptive effect is reduced.
  • They do not protect you or your partner against sexually transmitted infections, such as HIV and chlamydia.

The lactational amenorrhoea method

  • It becomes unreliable after six months.
  • You may find it inconvenient or difficult to breastfeed frequently.
  • It does not protect you or your partner against sexually transmitted infections, such as HIV and chlamydia.

Page last reviewed: 13/07/2011

For some women, natural family planning may not be the most suitable choice of contraception, and some women will not be able to use the lactational amenorrhoea method at all. For example:

  • If you have a medical condition that would make pregnancy especially dangerous, such as heart disease, you may want to choose a more effective method of contraception.
  • If you have a long-term condition that can affect your fertility signs, such as a thyroid problem or serious liver disease, it may be hard to use methods based on fertility awareness.
  • If you have a temporary condition that can affect your fertility signs, such as a vaginal infection, it may be hard to use methods based on fertility awareness.
  • If you are advised not to breastfeed - for example because you have viral hepatitis or HIV - the lactational amenorrhoea method will not be suitable for you.
  • If you find breastfeeding difficult, the lactational amenorrhoea method may not be suitable for you.
  • If you are taking a drug that affects the mucus from your cervix, such as a mood-altering drug, lithium, some antidepressants or anti-anxiety drugs, it may be hard to use a method based on your vaginal secretions.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

Browse Health A-Z