- If the instructions are properly followed, natural family planning methods can be up to 99% effective, depending on what methods are used. This means that one woman in 100 who use natural family planning will get pregnant in one year.
- It will be less effective if it’s not used according to the instructions – estimates suggest that it may only be around 75% effective because of mistakes.
- There are no physical side effects, and you can use it to plan when you get pregnant.
- You have to keep a daily record of your fertility signals, such as your temperature and the fluids coming from your cervix – it takes three to six menstrual (monthly) cycles to learn the method.
- Your fertility signals can be affected by factors such as illness, stress and travel.
- If you want to have sex during the time when you might get pregnant, you need to use a condom, diaphragm or cap.
- By using condoms as well as natural family planning, you’ll help to protect yourself against sexually transmitted infections (STIs).
How it prevents pregnancy
The aim of natural family planning is to prevent pregnancy by avoiding sex, or using barrier methods of contraception, during the woman’s fertile time. Natural family planning involves using your body’s signs and symptoms to assess if you’re currently fertile and likely to get pregnant if you have sex.
It is important that you are taught natural family planning by a suitably qualified teacher. You can check the availability of instructors in your local area by visiting the Fertility UK website.
The information in this section is designed to serve as an overview only. It is not a substitute for proper instruction and training.
There are three different fertility indicators you can use in combination to increase the effectiveness of natural family planning. These are:
- daily readings of your body temperature
- changes to your cervix – specifically, the secretions of mucus from your cervix
- the length of your menstrual cycle
These are discussed in more detail below.
Your menstrual cycle
Your menstrual cycle lasts from the first day of your period until the day before your next period starts. 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. The average length of the menstrual cycle is 28 days.
During your menstrual cycle:
- hormones are released to stimulate your ovaries
- a tiny egg stored in one of your ovaries begins to grow and mature
- when the egg is mature, it’s released from your ovary (a process called ovulation) and travels down the fallopian tube
Occasionally a second egg is released, within 24 hours of the first egg.
Ovulation occurs roughly halfway through your menstrual cycle, usually around 10 to 16 days before the start of your next period. Ovulation could happen earlier or later than this, depending on the length of your cycle.
When calculating your fertile time, you need to take into account the uncertainty over exactly when you ovulate.
For pregnancy to happen, a sperm needs to meet the egg to fertilise it. Sperm can live in a woman’s body for up to seven days after sex.
As the length of a menstrual cycle can vary over time, to make sure your calculations are as precise as possible, you will need to measure your menstrual cycle over the course of 12 months.
Calculating the length of your cycle is not a reliable way of working out your fertile time and should not be used on its own as a fertility indicator.
The temperature method
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 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:
- Taking your temperature every morning before you get out of bed. This should be done before eating or drinking anything, before smoking and ideally at the same time every morning.
- Look out for three days in a row when your temperature is higher than all of the previous six days. The increase in temperature is very small, usually around 0.2C (0.4F). It is likely that you are no longer fertile at this time.
Cervical secretion monitoring method
There is a change in the amount and consistency 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
- white and creamy
This is the start of the fertile period of your menstrual cycle. Immediately before ovulation the mucus will get:
- slippery, a bit 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.
Combining fertility awareness methods
It is best to combine all three methods to give you a more accurate picture of when you are likely to be most fertile.
You can use fertility charts to record information from all three methods, which you can then track over the course of each menstrual cycle. You can download fertility charts from the Fertility Education and Training site, with information on how to use them.
There are also apps you can download for smartphones or software for your computer that allow you to track this information.
How effective is natural family planning?
If natural family planning methods are used according to instructions, they can be up to 99% effective. This means that one out of 100 women using natural family planning correctly will get pregnant. It takes commitment and practice to use natural family planning this effectively.
Taking into account the fact that people can make mistakes, forget instructions or that other problems can occur, some estimates suggest that, in reality, natural family planning can be around 75% effective. This means that 25 out of 100 women using natural family planning may get pregnant.
If you 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 making sure you follow their instructions and advice.
Who can use natural family planning?
Most women are able to use natural family planning. However, there are some circumstances where it is not recommended as a form of contraception, or as your only form of contraception. You might want to consider a different method if:
- you have a medical condition that makes becoming pregnant dangerous – such as poorly controlled high blood pressure or heart disease
- there could potentially be a health risk to the baby if you got pregnant – for example, if you are dependent on drugs or alcohol, or taking medications known to cause birth defects
- you are having irregular periods, so predicting your fertile time may be hard or impossible; irregular periods can have a wide range of causes, such as age, stress, rapid weight gain or weight loss, excessive exercise and having an overactive thyroid gland
- you have a temporary condition that is disrupting the normal signs of fertility, such as pelvic inflammatory disease (PID), a sexually transmitted infection (STI) or bacterial vaginosis; you would have to wait until the infection passed before using natural family planning
- you have a long-term condition (or other underlying factors) that is disrupting the normal signs of fertility, such as liver disease, an over or underactive thyroid gland, cervical cancer or polycystic ovary syndrome (PCOS); find out more about things that affect your fertility signs
- you are taking a medication known to disrupt the normal production of cervical mucus, making fertility awareness methods difficult to use – this can include lithium (used to treat a number of serious mental health conditions, such as bipolar disorder) and some older types of antidepressants
- you have an increased risk of catching an STI – for example, you have multiple sexual partners
Things that affect your fertility signs
Some factors can disrupt normal fertility signs, for example if you:
- have irregular periods
- have recently stopped taking hormonal contraception
- have recently had a miscarriage or an abortion
- have recently given birth and are breastfeeding
- regularly travel through different time zones
- have an infection in your vagina such as thrush or an STI
Other factors that affect your body’s natural signs include:
- altering how and when you take your temperature
- drinking alcohol
- taking certain medication
- some long-term conditions
Advantages and disadvantages of natural family planning
- It does not cause any side effects.
- Natural family planning is acceptable to all faiths and cultures.
- Most women can use natural family planning, providing they are properly trained by a teacher in fertility awareness, and keep accurate records.
- Once you have learned the techniques, there should be no further need for input from health professionals.
- Natural family planning can be used to avoid pregnancy or to become pregnant, according to your wishes.
- It does not involve chemicals or physical products.
- It can help you recognise normal and abnormal vaginal secretions, so you can be aware of possible infection.
- It involves your partner in the process, which can help increase feelings of closeness and trust.
- Natural family planning does not protect against STIs such as chlamydia or HIV.
- You will need to avoid sex, or use contraception such as condoms, during the time you might get pregnant, which some couples can find difficult.
- If you do decide to abstain, there can sometimes be up to 16 days during which you cannot have sex, depending on your cycle.
- It can be much less effective than other methods of contraception. Depending on how accurately it is used, as many as one in four women using natural family planning may get pregnant.
- It will not work without the continuing commitment and co-operation of both you and your partner.
- It can take several menstrual cycles before you become confident in identifying your fertile time. During this time, you will have to use barrier contraception, such as condoms.
- You will need to keep a daily record of your fertility signs.
- It is not suitable if you have persistent irregular periods.
- Factors such as stress, illness, travel, lifestyle and use of hormonal treatments can disrupt your fertility signs. This includes oral emergency contraception. If you use the emergency contraceptive pill, you will need to wait for two complete cycles before relying on natural family planning again.
Lactational amenorrhoea method (LAM)
Women don’t have periods while they’re breastfeeding (this is known as lactational amenorrhoea), so breastfeeding can be used as a form of contraception. This is known as the lactational amenorrhoea method (LAM).
The fertility signals used in natural family planning methods are not reliable in women who are breastfeeding.
Women who are fully (or nearly fully) breastfeeding can use the LAM for the first six months after their baby is born, as long as:
- the woman has complete amenorrhoea (no periods at all)
- she’s fully or very nearly fully breastfeeding (this means that the baby is having breastmilk only, and very little or no formula)
- the baby is less than six months old
When used correctly and consistently, one in 200 women who use LAM will get pregnant in the first six months. However, take care to use the method correctly. Don’t feed your baby other foods because this may reduce your lactation.
LAM becomes unreliable when:
- other foods or liquids are substituted for breastmilk
- your baby reaches six months old
After having a baby, it is possible to get pregnant before your periods start again. This is because you ovulate around two weeks before your period. For more information on breastfeeding, LAM and other reliable methods of contraception, talk to your health visitor, midwife or doctor. You can also read about breastfeeding in the pregnancy and baby guide.
Where to get contraception
Most types of contraception are available free in the UK. Contraception is free to all women and men through the NHS. Places where you can get contraception include:
- most GP surgeries – talk to your GP or practice nurse
- Community Contraception Clinics
- GUM Sexual Health Clinic
- some young people’s services (call 0300 123 7123 for more information)
Contraception services are free and confidential, including for people under the age of 16.
If you’re under 16 and want contraception, the doctor, nurse or pharmacists won’t tell your parents or carer as long as they believe you fully understand the information you’re given, and your decisions. Doctors and nurses work under strict guidelines when dealing with people under 16.
They’ll encourage you to consider telling your parents, but they won’t make you. The only time that a professional might want to tell someone else is if they believe you’re at risk of harm, such as abuse. The risk would need to be serious, and they would usually discuss this with you first.