What is Natural Family Planning?

Natural family planning is a type of contraception which does not rely on any contraceptives but your awareness of your fertility. Couples who use the fertility awareness method track the woman’s cycle and they only have sex on days when conception is unlikely.

How Can I Prevent Pregnancy With Natural Family Planning?

In order to get pregnant, a man’s sperm has to reach an egg. There are certain days during the cycle when you are very likely to get pregnant if you have sex. This is the case around the time you ovulate, which means that your ovaries release an egg.

During other times of your cycle, your risk of pregnancy is low. There are certain signs which indicate whether you are fertile or not. If you want to rely on natural family planning, you need to learn those signs. The more signs you track and understand, the safer the method will be for you. It may take you several cycles before you are confident that youunderstand your cycle. You should use a barrier method (such as a condom) until you are sure that you know when you are fertile.

When Am I Fertile?

The menstrual cyclebegins on the first day of your period (the first day of bleeding). Over the course of a menstrual cycle, an egg matures and is eventually released (ovulation). This happens approximately halfway through your menstrual cycle. Depending on the length of your cycle, it can be between 10 and 16 days before your next period. Before you can use the fertility awareness method, you need to understand how long your menstrual cycle is.

How to calculate your fertile days

  • To calculate your fertile days, you should first track your menstrual cycle for about six months.
  • Take the length of your longest cycle and subtract 11 days to calculate your last fertile day.
  • Take the length of your shortest cycle and subtract 18 days to calculate the first day of your fertile period.


If your shortest cycle was 28 days and your longest cycle was 30 days your calculation would be as follows:

  • 28 days - 18 days = 10 days
  • 30 days - 11 days = 19 days

Now circle these dates in your diary. For example, in the example above, the fertile days are from day 10 to day 19. During this time, sex should be avoided. It is not advisable to go by timing only and you should also monitor other signs of fertility.

Signs of Fertility

Cervical Mucus

Your cervical mucus changes throughout your cycle and it gives a useful indication of your fertility. During the first days after your period when you are not fertile there will be little to no mucus. The closer you get to ovulation, the more cervical mucus you will notice. Normally, the mucus is white or creamy. Directly before ovulation it will be clearer and more liquid.

After ovulation, the mucus will become white or creamy and sticky again and within three days of this change you ought not to be fertile any more.


Your menstrual cycle causes small changes in your body temperature. After ovulation, your temperature will be 0.2°C (0.4°F) higher than usual for about three days. This indicates that you are no longer fertile in that cycle.

In order to take your temperature you need to buy a thermometer suitable for family planning, as most thermometers are not accurate enough. You need to take your temperature every morning before you get up, and before eating or drinking anything in order to get a valid result.

How Effective is Natural Contraception?

The effectiveness of natural family planning depends entirely on how much effort you put into monitoring signs of fertility and how strict you are about avoiding sex during the fertile days. Some sources claim, that natural contraception can be up to 99% effective if you follow all the advice and become an expert at observing relevant signs. If you have an irregular cycle however, it may not be suitable for you. It is also possible for your temperature to be affected by other factors (such as illness) and your cervical mucus may change due to infection (for example cystitis or an STI).

If you suffer from any medical conditions (or take certain medications) which affect your signs of fertility, your doctor will advise you to choose an alternative method. Before you start using this method, you should consult a doctor or nurse who will assess whether this method is right for you and give you the required training.

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