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Fertility awareness methods are techniques used to help someone determine when they are most fertile each menstrual cycle. Calendar (or rhythm), Mucus and Temperature are all types of FAM. While a combination of these methods may be used, the various centres that teach FAM may have differing opinions on the best ones.

FAM is based on the fact that a person with a uterus is fertile from a few days before ovulation until after ovulation has occurred. As sperm can survive in the uterus and fallopian tubes for up to 7 days, you are most likely to become pregnant if you have sex in the week before ovulation.

The aim of FAM is to recognise when ovulation is approaching (fertile phase begins) and when it has passed (fertile phase ends). The various methods of FAM use different signs to determine the beginning and end of the fertile phase.

FAM relies on the following facts

  • Ovulation occurs only once in each cycle.
  • Menstruation occurs 11-16 days after ovulation.
  • The egg lives 12-24 hours.
  • Sperm may live for up to 7 days in the uterus and fallopian tubes – this means that if you have sex as much as 7 days before ovulation you may still get pregnant.

This method of FAM estimates when ovulation will happen based on a record of past cycles. As cycle length can vary considerably, the calendar method is very unreliable and is not recommended to be used on its own.

A person calculates the length of their shortest and longest cycles, preferably over a period of at least six months. The first day of the period counts as Day 1.

Shortest cycle minus 20 = first fertile day
Longest cycle minus 10 = last fertile day

e.g. For someone with 26 to 31 day cycles

26 minus 20 = 6th day
31 minus 10 = 21st day

Those wanting to avoid pregnancy should not have unprotected sex between days 6 and 21 of their menstrual cycle.

The main use of this method is to provide a double check with another FAM on when fertile days may start.

This method instructs you in being able to identify the start and finish of your fertile phase by monitoring changes in your cervical mucus.

A person may be aware that, several days after menstruation, they have no noticeable discharge and their vulva feels relatively dry. As oestrogen levels rise approaching ovulation, there is a feeling of wetness at the vulva, with the mucus becoming clear, slippery, more watery and elastic (fertile mucus). Any of these changes mark the beginning of the fertile phase. You should avoid unprotected sex at this time if you wish to avoid pregnancy.

After ovulation the mucus once again becomes dry and sticky and you may notice a dry sensation at the vulva. Sex can be resumed after three consecutive dry days.

Note: vaginal infections or surgery of the cervix which interfere with production of mucus may affect the use of this method. Seminal fluid (semen) can also interfere with mucus readings.

The temperature of the body after at least three hours of rest is known as the Basal Body Temperature (BBT).

This is usually around 370C/98.60F, but it may vary slightly from person to person. Knowing what is normal for you will help determine your personal pattern of temperature shifts.

Before ovulation the BBT will be relatively lower. After ovulation, the BBT usually rises several tenths of a degree, and remains up until the menstrual period begins. Keeping a BBT record helps indicate when an egg has been released. When you see your temperature rise and remain higher for at least three days, you know that ovulation has occurred and your fertile phase has passed. When using the BBT method alone to avoid pregnancy, you must abstain from unprotected vaginal sex from the end of menstruation until at least three days of higher temperatures have been recorded.

Temperatures can be disturbed by different things such as fever, taking drugs, lack of sleep, travel, stress and electric blankets. It’s important to note these things on your daily chart, otherwise it’s possible to mistake them for a sign that ovulation has occurred. The temperature must be taken every morning immediately after waking and before getting out of bed, smoking, eating or drinking.

A digital thermometer is recommended because it measures small temperature changes accurately and quickly.


Some people may notice physical signs of ovulation with temperature and mucus changes. Recognising these changes may help you determine the time of ovulation.

Some of the signs are:

  • changes in the position of the cervix
  • softening and opening of the cervix
  • slight pain in the lower abdomen in the area of the ovaries, often on one side or the other
  • slight and temporary bleeding (spotting)
  • breast tenderness
  • a feeling of heaviness in the abdomen.

LAM is the use of breastfeeding as a contraceptive method. Breastfeeding has an effect on the production of hormones that reduces the probability of ovulation, which reduces the chance of pregnancy.

This method can be used by those:

  • who are fully breastfeeding (no artificial feeds, supplements or solids) and
  • whose baby is less than 6 months old and
  • who have not had any bleeding (other than during the first eight weeks following the birth).

Each method can be used alone, but if you combine different methods of FAM you may be able to more confidently determine your fertile phase.

It is difficult to be specific about effectiveness rates when it comes to FAM. Pregnancy rates vary depending on the particular group surveyed, whether one method or a combination of methods is used, and whether barrier methods are added during the fertile time. About 25 out of 100 people who are average users and who rely only on FAM become pregnant during the first year of use.

FAM is generally more effective for avoiding pregnancy when used consistently and correctly, with no vaginal sex during the fertile phase. If you decide to have sex during the fertile period, you can use barrier methods in order to reduce the chance of pregnancy.

To make a method or a combination of the methods work best for you, you should talk with a counsellor, take a class or read a book on FAM. There are also many great apps available for download.

Most people can use FAM. You don’t have to have regular cycles to use these methods, but those with regular cycles may have more success in avoiding/achieving pregnancy with FAM. FAM cannot be learned or used while you are taking birth control pills because the pill causes changes in the natural menstrual cycle. FAM isn’t hard to use, but you must understand how it works and be willing to put in the time and effort necessary to use it correctly.

  • Some people don’t have sex at all on fertile days.
  • Some people choose to have sex without having intercourse (e.g. oral sex).
  • Some people supplement FAM during fertile days by using various barrier methods, such as the condom or diaphragm.

Note: Spermicide can interfere with mucus patterns, so people using these products will need special instruction in order to continue using the cervical mucus method.

If you are worried that you have miscalculated your fertile time and had unprotected vaginal sex during an unsafe time, you may want to consider emergency contraception to reduce the risk of an unintended pregnancy.

Different methods of emergency contraception are available, such as emergency contraceptive pills and copper IUD. Emergency contraception is most effective when used as soon as possible after unprotected sex. Visit your doctor, pharmacist or ring the Sexual Health Helpline as soon as possible.

People should be aware that using an emergency contraceptive pill may affect their cycle pattern in subsequent weeks, making it more difficult to determine fertile times.

  • There are no health risks or side effects.
  • Can be used to prevent or plan a pregnancy.
  • Can be quite effective if used correctly.
  • Acceptable to those with religious concerns about birth control.
  • Free, except for possibly a thermometer, class fee and charts.
  • Can lead to a greater awareness and understanding of how the reproductive systems work.
  • People may find that using FAM leads to better communication and cooperation.
  • Learning FAM takes time and effort.
  • Using FAM requires a commitment to keeping careful note of daily body changes.
  • Even with correct use, the failure rate is often higher compared to other methods.
  • Both sexual partners must be prepared not to have vaginal sex, unless a barrier method is used, during the fertile time if they wish to avoid pregnancy.
  • Vaginal infections interfere with mucus detection.
  • FAM does not protect you from sexually transmissible infections (STIs).

Information last updated November 2019

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