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Natural family planning is when natural signs, such as body temperature, are used to identify when a woman is at her least and most fertile during each menstrual cycle, to help either avoid or plan pregnancy. This is known as fertility awareness.
There are a number of ways to assess whether it is likely that you are currently fertile. You can:
Read more about how natural family planning is performed.
In theory natural family planning can be up 99% effective in preventing unwanted pregnancies.
However, in practice natural family planning can be a complex procedure and it’s often possible to make a mistake when assessing fertility.
In reality natural family planning is estimated to be around 75% effective - so 1 in 4 women using this method of birth control may still become pregnant.
The same is also true of other methods of birth control. For example, male condoms are, in theory, 98% effective in preventing unwanted pregnancies, but in reality it’s more like 85% - so around 1 in 7 women using still become pregnant.
Read more about the results of natural family planning when compared to other methods of birth control.
Provided it’s followed correctly (usually with proper instruction from a trained natural family planning teacher) most women can use natural family planning effectively. There may be circumstances in which it is not recommended as a form of birth control, including:
Natural family planning requires commitment from both members of a couple so it may only be suitable for you if you are currently in a stable relationship.
Read more about who is best suited to using natural family planning.
Advantages of natural family planning include:
Disadvantages of natural family planning include:
Read more about the pros and cons of natural family planning.
Most women are able to use natural family planning. However, there are a number of circumstances where it is not recommended as a form of birth control, or as your only form of birth control.
These are described below.
The effectiveness of birth control methods are measured in two ways, perfect use and typical use.
A perfect use measurement is based on how effective the birth control method would be if the instructions for use were followed exactly as recommended.
However in the real world people can make mistakes, forget instructions and other problems can occur. So a typical use measurement is based on what you’d expect to see in a more realistic setting.
The perfect use percentage of natural family planning is very good at 99%; out of a 100 women using that method only one would become pregnant.
But the typical use percentage – possibly due to the complexities involved – is less effective at 75%; out of a 100 women using that method 25 would become pregnant.
The perfect and typical use percentages of other types of birth control are listed below:
If you do decide to use natural family planning you can reduce your risk of accidental pregnancy by making sure you are taught natural family planning by a suitably qualified teacher and then ensuring you follow their instructions and advice.
The pros and cons of using natural family planning as a method of birth control are described below.
The advantages of using natural family planning methods include:
The disadvantages of using natural family planning methods include:
It is important that you are taught natural family planning by a suitably qualified teacher.
The information in this section is designed to serve as an overview only. It is not a substitute for proper instruction and training.
The key to natural family planning is to use the signs and symptoms of your body to assess if you’re currently fertile and likely to get pregnant if you have sex.
Three different methods are used in combination to increase the effectiveness of this form of birth control. These are:
Each method is discussed in more detail below.
Your menstrual cycle lasts from the first day of your period up to, but not including, the first day of your next period. The length of a woman’s menstrual cycle can vary. Anything from 24 to 35 days is common, although it could be longer or shorter than this. On average, it lasts 28 days.
During your menstrual cycle, hormones are released to stimulate your ovaries. An egg stored in your ovaries begins to grow and mature. When the egg is mature, it’s released from your ovaries (ovulation) and travels down the fallopian tubes.
Occasionally, more than one egg is released.
Ovulation occurs roughly halfway through your menstrual cycle, usually around 10 to 16 days before the start of your next period.
Hormones will also cause the lining of your womb to thicken in order to receive the egg. If the egg isn’t fertilised with sperm, the lining of your womb will break down leading to a period.
An egg can only survive for 24 hours but sperm can survive in your womb for up to seven days, so depending on how soon ovulation followed ejaculation your may be fertile for up to eight days.
When calculating your fertile time, you need to take into account the uncertainty over exactly when you release eggs during your menstrual cycle,.
As the length of a menstrual cycle can vary over time, to ensure your calculations are as precise as possible you will need to measure your menstrual cycle over the course of six months.
One way of doing this is known as the calendar method, which .involves the following steps:
For example if your shortest cycle was 25 days and your longest cycle was 33 days:
The temperature method is based on the fact that there is a small rise in body temperature after ovulation takes place.
You will need to use either a digital thermometer or a thermometer specifically designed to be used for natural family planning, these are available from pharmacies. Ear or forehead thermometers are not accurate enough to be used in this way.
The temperature method involves:
There is a change in the consistency and amount of the mucus secreted from your cervix during different times in your menstrual cycle.
You can check this by gently placing your middle finger into your vagina and pushing it up to around your middle knuckle.
For the first few days after your period you will probably find that your vagina is dry and you cannot feel any mucus. As the levels of hormones rise to prepare your body for ovulation, you will probably find that your cervix is now producing mucus that is moist and sticky and is white and creamy in colour. This is the start of the fertile period of your menstrual cycle.
Immediately before ovulation the mucus will get wetter, slippery and clearer; much like raw egg white. This is when you are at your most fertile.
The mucus should then soon return to being thicker and sticky and after three days you should no longer be fertile.
There are a number of factors that can disrupt normal fertility signs (see below) so relying on just the one method is not recommended.
It is best to combine the all three methods to give you a more accurate picture of when you are likely to be most fertile.
There are fertility charts that allow you to record information from all three methods which you can then track over the course of each menstrual cycle.
An example of fertility charts and information on how to use them can be found at the Fertility and Education website.
There are also a number of apps you can download for smartphones or software for your computer that allow you to track this information.
Your fertility signs can be disrupted if you:
Other factors that affect your body's natural signs include:
Read more about who may not be suited for natural family planning.
Ovaries are the pair of reproductive organs that produce eggs and sex hormones in females.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.