Fertility awareness

What is fertility awareness?

Natural family planning is a method used to plan or prevent pregnancy by recognising the signs of fertility in your menstrual cycle. If you have irregular periods, fertility is hard to track.

How does fertility awareness work?

By understanding your menstrual cycle and how it affects your body, you can work out when you’re fertile and when to have sexual intercourse to start a pregnancy or when not to have sexual intercourse if you want to prevent a pregnancy. 

For the natural family planning method to work effectively, it's best that you’re taught how to do it by a trained healthcare provider. Talk to your healthcare provider to find out where you can get education and support.

The signs of fertility include:

• the length of your menstrual cycle and time of ovulation
• your daily body temperature
• changes to your cervical secretions or cervical mucus. 

By learning about and tracking these, you can then plan when to have sexual intercourse in order to plan or prevent pregnancy. 

If you’re not sure if you’re fertile or not when you want to have sex, it’s best to use a condom or avoid vaginal sex if you don’t want to get pregnant.

Your menstrual cycle and ovulation

Your menstrual cycle lasts from the first day of your period until the day before your next period starts. The average cycle is about 28 days, but it can be shorter or longer (between 21 and 35 days is normal). Ovulation happens about 14 days before your next period starts, when an egg is released from one of your ovaries and travels down the fallopian tube. In a 28-day cycle this is usually day 14, but the timing may vary. Occasionally, a second egg is released within 24 hours of the first egg – a process known as double ovulation. 

After your egg has been released, it can live in your body for about 12 to 24 hours. A sperm must meet your egg within that time period for pregnancy to happen. You can get pregnant for up to 2 days after you ovulate if double ovulation has occurred. 

It's also possible to get pregnant if you've had sexual intercourse in the 5 days before your egg is released. This is because sperm can live for up to 5 days in your womb.  

The length of your menstrual cycle can vary over time. To have a good understanding of your menstrual cycle, track it for 12 months. Then you can calculate when you’re most likely to be fertile to prevent or plan a pregnancy. However, you may need to allow for uncertainty about exactly when you ovulate. You may know when you ovulate because you get sharp or dull crampy pain on the side where the ovary is releasing an egg. You may also have light bleeding at this time.

Your body temperature

After ovulation, your body temperature rises a little. The rise in temperature is very small, around 0.2° to 0.5° Celsius. Therefore, measuring your daily body temperature helps you to find out when you are or are not fertile. You need to use a digital thermometer or a thermometer specifically designed for natural family planning. Ask your pharmacist or healthcare provider for more details. 

You need to measure your temperature at the same time every morning, before you get out of bed. If you notice your temperature is higher it may be that you have just ovulated, if it’s been higher for 3 days in a row (than in the previous 6 days), then it's likely that you’re not fertile at this time. However, there are a lot of factors that can also affect your body temperature, including:

• medicines such as paracetamol
• illnesses such as colds, flu or other infections.

Your cervical secretions or cervical mucus 

Your cervical secretions or mucus can change throughout your menstrual cycle. Your cervical mucus is moist, sticky, white and creamy as your hormone levels rise and your body is preparing for ovulation. Your fertile period starts around this time.

Then, immediately before ovulation, your mucus becomes clearer, wetter and slippery, like raw egg white. This change is to allow sperm to swim through it to meet an egg. This is the time when you’re most fertile.

After ovulation, your mucus will become thicker and sticky again, and you should no longer be fertile after 3 days.

Video: The menstrual cycle and your body’s natural signal of fertility – cervical mucus

Get advice from somebody who is trained in the fertility awareness method. If you’re trying to avoid pregnancy, use a barrier method of contraception, such as a condom, when you’re still learning how to follow it. 

Three specific methods have been developed, all of which are designed to be used with a trained educator rather than by couples by themselves. Educators for the first 2 are available in Aotearoa New Zealand.

The Sympto-thermal Method (STM) can be very effective if it’s taught by an accredited fertility educator and used consistently and correctly. It uses basal body temperature, cervical mucus and vaginal sensation recordings. It’s taught by Natural Fertility NZ educators over 3 sessions. Find an educator to learn more.

The Billings Ovulation Method (BOM) is a patented approach to identifying and recording natural signs of fertility. It was developed by doctors who wanted to enable women to achieve or avoid pregnancy, and look after their reproductive health by being able to pick up changes that might need checking. It involves monitoring and recording menstrual bleeding, mucus patterns and vulval sensations to identify times when you’re fertile and infertile. The method uses a chart with symbols or stamps to represent what happens each day.

An accredited instructor provides training (typically 4 to 6 sessions), in a clinic setting, as a home visit or online depending on where you live.

Success with this method depends on:

• good understanding and teaching from an accredited teacher
• daily observation and charting
• following the 4 simple rules to achieve or avoid pregnancy
• cooperation between partners.

Learn more about the Billings Ovulation Method(external link).

The Creighton Method Fertility Care System (CrM or CrMs) is similar to the BOM but involves a more detailed approach to describing and recording cervical mucus. Find out more about the CrMs(external link).

You can use this method to plan or prevent pregnancy. However, there are factors that can affect the signs of fertility which will reduce how well this method works.

These include:

• irregular periods – which make it hard for you to calculate when you’re ovulating
• having sexually transmitted infections (STIs) or pelvic inflammatory disease (PID)
• medicines that affect your cervical mucus (eg, antihistamines or vaginal creams)
• if you used hormonal contraception in recent months
• recent miscarriage or abortion
• recent delivery of a baby or breastfeeding
• being a heavy alcohol drinker 
• having irregular sleep or work schedules or travelling a lot
• not being able to take your temperature at the same time before you get out of bed every morning.

The natural family planning method is not recommended:

• when your fertility signs are hard to read
• if you can't use barrier contraception or avoid sex on fertile days
• when an unplanned pregnancy would be a serious health risk
• if you’re taking medicine that could be harmful in pregnancy.

If used correctly, natural family planning can be up to 99% effective. This means out of 100 women who follow natural family planning perfectly for 1 year, only 1 will get pregnant. 

In real life, more women than this get pregnant using natural family planning for preventing pregnancy. Most studies show that between 2 and 23 out of every 100 women using these methods will become pregnant each year. Some studies report even higher rates, up to 34 pregnancies per 100 women per year, depending on the method and the group of people studied.

Some of the reasons for this include:

• not being taught the method correctly
• not understanding how to use the method
• having difficulty recognising the signs of fertility
• having sexual intercourse during the fertile time.

The benefits of natural family planning include:

• no side effects
• it's acceptable to all faiths and cultures
• most women can use the method, as long as they get training 
• it can be used either to plan or prevent pregnancy
• no chemicals or products are involved
• recognising normal and abnormal vaginal secretions makes you more aware of possible infection
• an improved relationship between you and your partner as the method requires the commitment of your partner too.

Similar to other contraceptive methods, natural family planning has disadvantages if it's not followed correctly.

These include:

• unplanned pregnancy
• sexually transmitted infections if you don't use a condom
• it's much less effective at preventing pregnancy than other methods (such as long-acting reversible contraception) if not followed correctly 
• it takes time for you to learn and be confident in identifying your fertile time
• the need to practice and for continued commitment
• the need to keep a daily record of your fertility signs
• that there are other factors affecting your fertility signs
• the need to use other methods of contraception or avoid sex when you are fertile. 

Natural Fertility NZ(external link) specialises in teaching individuals and couples about natural fertility and how it relates to the menstrual cycle. There are also education sessions for health professionals. Phone 0800 101 637 or email [email protected] to find out more.