Natural birth control methods teach women to determine the fertile phase (typically 7 to 10 days long) of their menstrual cycle. To avoid pregnancy, women avoid intercourse on fertile days.
There are many variations of natural birth control. The most effective methods teach women to chart the signs of fertility that ebb and flow with the natural hormonal changes of each menstrual cycle.
There are two main approaches 1) the sympto-thermal approach where waking temperature and cervical mucus are charted, and 2) the mucus approach where only cervical mucus is charted.
It is helpful for women and their partners to know about the two most common methods:
- Fertility Awareness Method (FAM) refers to a natural birth control method outside of a religious framework that supports the use of barrier methods (condom, diaphragm, and spermicide), emergency contraception, and abortion.
Justisse is a Canadian developed variant of FAM that teaches both the mucus only and the sympto-thermal approaches.
- Natural Family Planning (NFP) typically refers to natural birth control that is taught and practised within a religious framework, most commonly Catholic centred organizations. It does not support the use of barrier methods, emergency contraception, or abortion.
Billings Ovulation Method teaches only mucus observations. Serena and Couple to Couple League methods are sympto-thermal NFP variants. The Creighton Model will teach both mucus only and sympto-thermal approaches.
A woman can get pregnant if a man’s sperm reaches one of her eggs (ova). Contraception tries to stop this happening by keeping the egg and sperm apart or by stopping egg production. One method of contraception is natural family planning.
Lactational amenorrhoea method (LAM)
Natural family planning is a method that teaches you at what time during the month you can have sex without contraception and with a reduced risk of pregnancy.
It works by plotting the times of the month when you’re fertile and when you’re not.
You learn how to record fertility signals, such as your body temperature and cervical secretions (fluids, or mucus), to identify when it’s safer to have sex. Natural family planning is more effective when more than one fertility signal is monitored.
You can’t learn natural family planning from a book. It has to be learned from a specialist teacher.
At a glance: facts about natural family planning
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 methods you can use in combination to increase the effectiveness of natural family planning. These are:
- calculating where you are in your menstrual cycle
- taking daily readings of your body temperature
- monitoring changes to your cervix, specifically the secretions of mucus from your cervix
Each method is 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 six months. One way of doing this is known as the calendar method.
This involves the following steps:
- record the length of your menstrual cycle every month for six months
- 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, or use a condom or diaphragm if you do have sex
For example, if your shortest cycle was 25 days and your longest cycle was 33 days:
- you would take away 18 from 25 to give 7
- you would take away 11 from 33 to give 22
- so you should avoid having sex from day 7 to day 22 of your menstrual cycle
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 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:
- 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
- 0.2°C (0.4°F). 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.
How natural birth control works
The FAM/NFP sympto-thermal method is explained below. It is considered the most effective of all the natural birth control methods.
Sympto-thermal teaches a woman how to observe, chart and interpret her waking temperature (basal body temperature or BBT) and cervical mucus to understand what days she is fertile and what days she is not fertile. She then knows when she is likely and when she is less likely to become pregnant from intercourse.
A woman who has a regular menstrual cycle will usually experience the following sequence of events:
- 3 to 7 days of menstruation
- several days where she does not feel or see mucus in her vagina or on her vulva
- several days of a ‘wet’ or ‘slippery’ sensation at her vulva or in the vagina where she sees and/or feels mucus, which becomes progressively more slippery,
- stretchy, and clear as ovulation approaches
- after ovulation her waking temperature rises, mucus disappears from the vulva, and the vulva and vagina feel “drier
Fertile days begin with the first sensation of mucus at the vulva and continue until both the mucus has dried up and the waking temperature has been high for 3 days in a row. With days of higher fertility and lower fertility determined, a woman can time intercourse to avoid or achieve pregnancy.
If a woman’s cycle does not follow a typical pattern, using natural birth control will be more difficult. However, she can still use natural birth control but she is advised to seek consultation with a trained FAM/NFP instructor in order to use the method most effectively.
In general, FAM/NFP are not recommended for women with the following difficulties: irregular cycles, inability to interpret the fertility signs correctly, or persistent infections that affect the signs of fertility.
Cervical changes are a third fertility sign that a woman may find useful in determining her fertility. She checks for variations in the position, firmness and openness of the cervix that relate to fertile and infertile days.
In order to effectively use FAM/NFP a woman needs to accept responsibility for charting and interpreting her fertility on a day-to-day basis. The possibility of an unplanned pregnancy should not represent a devastating occurrence in order to use this method of family planning.
As with all forms of birth control, motivation, intention, and cooperation between partners are the key to effective, successful use.
Successful use of FAM/NFP methods depends on the accuracy of the method in identifying the woman’s actual fertile window, a woman’s/couple’s ability to correctly identify the fertile time, and the couple’s ability to follow the instructions of the method they are using.
The effectiveness of FAM/NFP(Strauss and Barbieri 2004, Hatcher 2004.) varies depending on the method:
- 95-98% effective with perfect use (user strictly follows rules to avoid pregnancy)
- 75-88% for typical use (user may not always follow rules)
Benefits of FAM/NFP
- Effective method of birth control
- Has no negative health side effects
- An alternative for women who cannot or do not want to use hormonal methods
- Promotes positive body awareness
- Consistent with many religious beliefs and lifestyles
- Alerts women to reproductive health and fertility concerns
- Fosters communication between partners
- Encourages partners to enjoy a variety of romantic or sexual activities as alternatives to vaginal intercourse during fertile periods
- Encourages male involvement