Busting the myths about the symptothermal method

The sympto-thermal method is a natural approach based on observing fertility throughout your cycle. It primarily uses two indicators: temperature tracking and observation of cervical mucus. It can be used as a natural contraception method or as a conception aid.

The aim of sympto-thermal method is to observe changes to determine whether ovulation has occurred and when, rather than to predict when it will happen. It is also a method for observing your overall health — to get to know yourself, to recognise the different hormonal phases you go through, and to understand their duration. 

The sympto-thermal method is an age-old approach that emerged as a reaction to the contraceptive pill, which the Church considered to be "against the body". The Church then commissioned scientists to work on natural methods of birth spacing. From this research emerged methods of observing the female cycle (cycle awareness methods), notably through the observation of temperature and cervical mucus.

Although the sympto-thermal method is as established as the contraceptive pill, it has evolved — particularly with the advent of modern tools such as electronic thermometers and smartphone apps. It is a scientifically proven method, supported by extensive research on the subject.

The sympto-thermal method does not impose a strict lifestyle — for example, temperature does not have to be taken at the same time every day.

We must take our temperature at the same time and every day - FALSE

When it comes to taking your body temperature, it doesn't need to be done every day. With practice and habit, it is possible to take as few as 10 temperature readings (roughly one third of the cycle). Temperature taking begins after your period, up until the close of the fertility window.
 

The aim is to identify the follicular phase (that is, the preparation for ovulation). At least 6 temperature readings are needed. As soon as temperatures rise over 3 to 4 days, ovulation has passed. Temperature readings can then stop, resuming only on the sixth day of the next cycle.
 

Temperature should be taken upon waking (there's no need to set an alarm at the same time every day) as this is when our body temperature is at its lowest during the day. When we wake up, we are in the same basal condition, which allows us to compare temperature readings.
 

What if I get up at 7:00 every day but at 11:00 on Sunday morning?
There's no need to take your temperature every day — so you can skip it on a Sunday!
 

A standard thermometer is sufficient for practising sympto-thermal method - FALSE

To take your temperature, you need a specific thermometer with a precision of two decimal places, known as a "basal thermometer". This precision is essential to ensure the reliability of the method.
 

Temperature must be taken rectally - FALSE
 

Temperature can be taken orally, rectally, or vaginally. "Internal" temperature taking (via "internal" orifices) is the only method that has been studied for reliability. As for the rest — connected bracelets or forehead thermometers — their readings are often not precise enough, and some use algorithms that interpret and adjust the temperature by a few degrees.

We tell you more about these techniques in our article ovulation symptom. 

A cycle does not always last a month. When you are on the pill, your cycle is regulated in a certain way, but otherwise there is no reason why you should have your period on the same days every month and at the same time, as natural variations exist. A normal cycle can range from 23 to 35 days, and cycles are considered regular when they vary by no more than 7 days.

Our female cycle is like a year, with 4 seasons: spring, summer, autumn and winter. The 21st of June is the first day of summer, but sometimes it is sunny on the 21st of June, and sometimes it rains. 

From one cycle to the next, there can be variations of a few days, just as there are from one season to another.
 

A cycle can range from 23 to 35 days.
 

Our cycle has 4 main phases:
- Menstruation: 2 to 6 days.
It is a great reset, the resting phase of the cycle.
- Preparation for ovulation: at least 6 days.
Our body needs time to wake the follicles (future eggs). Oestrogen is the dominant hormone during this phase, stimulating the follicles to grow until they reach the size of an egg. We are generally fertile 5 days before ovulation and 1 day after (as the egg does not survive for long).
- Ovulation: approximately 1 day.
This is the moment when the egg is released, becomes available and then travels up the fallopian tube to await fertilisation. This is when we are at our most fertile.
- Post-ovulation: between 11 and 16 days.
 

The luteal phase is dominated by progesterone, which has numerous effects — particularly on our fertility signs. Cervical mucus changes in appearance and body temperature rises.
 

In "calendar" methods such as the Ogino method, this phase is said to last a fixed 14 days. In reality, however, there is no reason why this should be the case — its duration can vary from 11 to 16 days, though it tends to be fairly consistent for the same woman.

To find out more, read our article on how to calculate your ovulation. 

I am fertile all the time, I can get pregnant at any moment – FALSE

The luteal phase, after ovulation, is completely infertile until the start of the next cycle. You therefore cannot get pregnant throughout the entire cycle. It is men who are fertile all the time.

I am infertile during my period – FALSE

It is important to be wary of the belief that "I have my period, so I'm protected." Generally speaking, we are infertile during menstruation, but this also depends on our cycle.
If, for example, your cycles are a little short and ovulation occurs a little early, you may be fertile from the very first days of your period.

Ovulation does not take place during a period, but sperm can survive for several days in the cervix. So if you have sex towards the end of your period, sperm can stay alive until ovulation occurs and lead to a pregnancy. Blood is not a spermicide!
 

I am infertile because I am breastfeeding – NOT ALWAYS TRUE

Breastfeeding may or may not affect fertility!
 

Prolactin, one of the breastfeeding hormones, can suppress ovulation for a period of time. It is the baby's suckling that stimulates its production. The suppression of ovulation varies from one woman to another.
 

There is a close correlation between the frequency and duration of feeds, on the one hand, and plasma prolactin levels, on the other. It is estimated that breastfeeding with at least 6 feeds per 24 hours (day and night) with a total duration of 65 minutes suppresses ovarian activity (HAS, Allaitement maternel – Mise en œuvre et poursuite dans les 6 premiers mois de vie de l'enfant). This is the MAMA method (Lactational Amenorrhoea Method).
 

The return of periods marks the restart of fertility, even if the cycle is often still a little unpredictable at first. It is worth noting that even in the absence of a first period, ovulation can still occur beforehand (in around 5% of cycles). In that case, it happens one to two weeks before periods return. Even if in most cases the first cycles after the return of periods are not optimal for implantation, you should still take care if you do not want another pregnancy! 

Fertility and emotions are two separate things – FALSE

The same part of the brain manages both emotions and hormones. This explains why when we are overwhelmed by emotions, the fertility function pauses. Situations such as moving house, a change of job, an important exam, a partner's absence, or a lockdown… are often behind delayed or absent ovulation, which can compromise the chances of achieving a positive pregnancy test !

If the cycle is irregular, it is because the follicular phase is irregular. The post-ovulation phase, however, is generally very regular. The symptothermal method works very well with irregular cycles, but it is important to be well acquainted with the specificities of the condition and the method.

If your period is 7 to 15 days late, it is often because ovulation was delayed by 7 to 15 days.
 

The post-ovulation phase lasts between 11 and 16 days; beyond 16 days, if the temperature remains high, pregnancy may be suspected.
 

If you have irregular periods and/or PCOS, symptothermal method can be a good way to get to know your cycle better.

I have periods whilst on the pill — NOT ENTIRELY TRUE

When you bleed whilst on the pill, it is due to hormonal variations. This is not a period in the true sense, but rather a withdrawal bleed from synthetic hormones. For example, if the pill packet lasted 35 days, we would have our "period" every 35 days.
Without ovulation, there is no "cycle", and therefore no periods.

As soon as I stop the pill I can observe the cervical mucus parameter in the symptothermal method — FALSE

After stopping the pill, not all women immediately notice cervical mucus that resembles "egg white" at ovulation. After years on the pill, cervical mucus tends to be of poorer quality (whitish and only slightly stretchy).

After stopping the pill, it takes approximately 6 to 8 months (at minimum) before a healthy cycle is restored, as the body needs time to clear all synthetic hormones. But this is not necessarily a straightforward process — to find out more, read our article: The truth about the pill.

First of all, when we talk about cervical mucus, we often refer to white discharge.

White discharge, or leucorrhoea, is white fluid visible at the vulva. Cervical mucus comes from the cervix. It is produced by cells that are subject to hormonal variations. These cells produce different types of cervical mucus at different points in the cycle. Symptothermal method therefore helps you learn to recognise the different types of cervical mucus throughout your cycle.
 

We can observe our cervical mucus at the vulva, for example when we go to the toilet. It is also visible at the entrance to the vagina, or at the level of our cervix.
 

Cervical mucus lines the vagina to make it welcoming for sperm. It protects sperm from the natural acidity of the vagina. It also helps sperm travel up into the lower cervix and provides them with nutrients while they await ovulation. So as soon as you have cervical mucus, you are potentially fertile.
 

Our cervical mucus will have different textures and appearances depending on the time of the cycle:
- Cervical mucus at the end of your period and then after ovulation
Appearance: rather whitish or even yellowish, thick, opaque, lumpy, pasty, non-elastic, solid
Sensation: dry, no moisture or discharge (you won't see any cervical mucus as it won't flow, and this is perfectly normal!)
- Cervical mucus at the start of the fertile window
Appearance: white or yellow, creamy, pasty/cloudy, milky, viscous
Sensation: wetter (but not quite to the point of discharge)
- Cervical mucus at the peak of fertility
Appearance: very fluid, slippery, clear or even translucent and watery (like water — sometimes mistaken for water), or stringy and shiny (like egg white), elastic and stretchy
Sensation: wet, slippery, lubricated when you wipe (it flows)

The cervical mucus after fertilisation is specific. 

Just like oestrogen and progesterone, the LH hormone plays a role in the cycle. It is the one that triggers ovulation. An LH surge occurs 24 to 36 hours before ovulation.
 

Please note that LH tests (or ovulation tests) do not prove that ovulation has occurred, but simply that LH is present in the body.
 

In the practice of symptothermal method, LH tests are unnecessary because the aim is not to know when LH is present, but when ovulation actually occurs.

When pregnant, you can also continue to track your temperature, particularly during the first trimester. At that stage, you can take your temperature every 2 to 3 days to observe whether your pattern remains stable.

With sympto-thermal method tracking, you can even confirm a pregnancy without a pregnancy test by observing that your temperature remains elevated beyond 21 days.