Cervical mucus is a secretion produced by the cervix, which is the lower part of the uterus that connects to the vagina. It plays a crucial role in fertility and reproductive health. The consistency, colour, and amount of cervical mucus change throughout a woman’s menstrual cycle, reflecting changes in hormone levels. Cervical mucous is the main biomarker used in fertility awareness methods to help monitor fertility in real time. In order to correctly use cervical mucous as a biomarker of fertility women must resist the urge to predict ovulation with algorithms and different calculations and simply observe the changes in their cervical mucous as it is happening.
Function of cervical mucus:
The primary function of cervical mucus is to provide a natural barrier that prevents bacteria and other harmful substances from entering the uterus. It also helps to nourish and protect the sperm during their journey through the female reproductive tract. Additionally, cervical mucus plays a crucial role in fertility by creating a hospitable environment for the sperm to survive and swim towards the egg.
There are different types of cervical mucus that a woman can observe during her menstrual cycle. The types of cervical mucus can vary in consistency, colour, and amount. When charting cervical mucous “sensation at the vulva” is considered a more important way to measure cervical mucous than observing the mucous itself. This is because at certain times of a woman’s life eg. breast-feeding and peri-menopause (when estrogen is low) there is a loss in cervical mucous production. Sometimes no cervical mucous is observed externally but the sensation is still felt internally meaning that ovulation/pregnancy is still possible. Additionally, many women get confused and overwhelmed over correctly identifying the look of cervical mucous in their underwear or on the toilet paper, but find it easier to identify a change in sensation at the vulva. For these reasons, sensation at the vulva is a more important marker of fertility and the reasons I ask my clients to focus on sensation over cervical mucous observation.
Identifying Basic Infertile Pattern:
The basic infertile pattern is the period of time after menstruation when estrogen levels are low and the cervix is blocked and so pregnancy does not occur. For most women with regular cycles, this period of time lasts 2-3 days but may last longer in cases of delayed ovulation or in the case of early ovulation may not occur at all. Women with early ovulation can be fertile on their periods and due to blood being mixed with fertile cervical mucous, fertility is difficult to observe. There are 3 main types of basic infertile pattern are:
- no mucus or dryness sensation
- an unchanging low volume discharge at the vulva
- oscillation between dry/no discharge and some low volume patchy mucous from time to time.
It is crucially important for the woman to identify her own unique basic infertile pattern in order to be able to recognise the “point of change” which occurs at the first presence of cervical mucous. This opens up the fertile window. The majority of women fall into the “dry or no mucous” category which makes identifying the pattern easier, but many women don’t and may find it difficult to assess when their fertile window begins. The main characteristic feature of the basic infertile pattern is that it is unchanging. Even if there is some discharge, the volume and consistency of the discharge is the same until the point of change. This is because the basic infertile period is responding to unchanging low levels of estrogen. As soon as estrogen begins to rise (due to signal of FSH from the brain), cervical mucous will also change and open the fertile widow. If the basic infertile pattern can be identified easily, a woman can easily identify the start of her fertile window, however according to the Sensiplan method, some additional calculations can be made to help assume fertility. For beginners the “5 day rule” method can be applied, where the first 5 days of the menstrual cycle (day 1 is the first day of period bleeding) are assumed infertile UNLESS there is felt presence of cervical mucous or if ovulation is known to occur prior to day 12. For experienced charters that have been charting for at least 12 months, the minus 8 rule can be applied, where you minus 8 days away from the earliest observed temperature recording based on the previous 12 cycles, keeping in mind that ovulation changes and can occur very early in the cycle in times of peri-menopause when estrogen is very high. It is also completely acceptable and recommended that a woman can use a barrier method the entire first half of her cycle until 3 days after ovulation is confirmed.
Types of cervical mucous:
One of the most difficult things about learning fertility awareness method for many women is learning to identify the type of cervical mucous they have at different stages of the menstrual cycle. Much of the information online likes to put women into neatly defined boxes of the type of mucous and sensation things they should be expected to see and feel at different stages. The truth is that these guidelines may work for some women but they do not work for everyone. Learning fertility awareness is not about trying to make your body fit into a set of rules, but rather learning your own body and the signs that it gives you. This is why it is important for women to use language that makes sense to them and to recognised their own patterns.
The three most common types of cervical mucus are:
- Dry or sticky cervical mucus/ Non Fertile Mucous: This type of cervical mucus is thick and tacky, making it difficult for sperm to survive. It is typically observed in the first few days after the end of a menstrual period and 2-3 days after ovulation until the arrival of the next period. Three days after ovulation a “mucous plug” is formed at the cervix. This is when the cervical mucous closes entry to the cervix and makes it impossible for sperm to enter. Pregnancy is not possible during this stage. The mucous plug starts to disintegrate just prior to the arrival of the next period. During this phase the sensation at the vulva is dry and rough. Often nothing is observed, however thick, tacky, dry and crusty mucous can be observed on underwear or during a wipe.
- Creamy cervical mucus/Non Peak Mucous: This type of cervical mucus is opaque and creamy in texture. The first observation of non peak cervical mucous opens the fertile window and is known as the “point of change.” This mucous is usually observed during the early part of the menstrual cycle (follicular phase) when estrogen levels are low but have started increasing. This type of cervical mucous is only partially fertile. Its main function is to trap malformed sperm and filter them out to ensure only the healthiest sperm make it to the egg. On occasion this type of mucous is also seen AFTER ovulation during the second mini estrogen rise. If ovulation has been confirmed, this is not a fertile period of time and is just a reflection of estrogen levels. The sensation at the vulva with this type of mucous is moist/damp. Cervical mucous appears sticky or creamy and is often white or yellowish in colour.
- Egg white cervical mucus/Peak Cervical Mucous: This type of cervical mucus is clear and stretchy, resembling the consistency of raw egg whites. It is typically observed close to ovulation, which is the time when a woman is most likely to conceive. This type of mucous is most favourable to sperm survival and is most likely to result in pregnancy. The sensation at the vulva is wet, slippery, slimy. This type of cervical mucous is highest in water content and can appear wet, stretchy and translucent in colour.
Charting cervical mucous with irregular cycles.
With regular cycling women, cervical mucus can be used to identify the fertile window, which is the period when a woman is most likely to conceive. The fertile window usually lasts for about six days, starting five days before ovulation and ending on the day of ovulation. For women with irregular cycles, detecting the fertile window can be challenging, especially when there are multiple days of fertile/peak cervical mucus. This can be seen in women with PCOS, breastfeeding mums, women who have recently discontinued hormonal birth control, and under periods of stress. Even women with regular cycles can experience multiple days of fertile/peak mucous in what is known as a ‘stress patterned menstrual cycle.” Multiple days of fertile/peak cervical mucous occurs because the body tries to ovulate but fails. Each month a group of eggs are released from the ovary to develop and mature and only one of them is selected to ovulate, the rest die and get reabsorbed into the body. If the body fails to ovulate, one of the other eggs is selected to mature and ovulation is attempted again. This is observed by fertile cervical mucous that seems to be reaching its peak but never dries. Instead the amount of cervical mucous decreases and then increases again like a wave. In women with PCOS, this manifests “multiple LH surges.” Luteinising hormone (LH) is the hormone responsible for triggering ovulation however if ovulation does not occur, multiple LH signals are sent to the ovaries to try and establish ovulation.
When charting with irregular cycles or multiple days of fertile/peak mucous, it is important to treat each day of observed mucous as potentially fertile. There is no way of knowing when the body will actually ovulate and so it is important to chart in real time and assume fertility. This can be very frustrating for women who take months to ovulate as they must continue to use a barrier method if trying to avoid pregnancy. It can also be frustrating if attempting to conceive as the timing of intercourse to coincide with ovulation is very hard to predict.
What can interfere with cervical mucous charting?
There are several factors that can interfere with the interpretation of cervical mucus,
- Semen after sexual intercourse: After sexual intercourse, semen can mix with cervical mucus, making it difficult to identify changes in cervical mucus consistency and colour. It is best to wait at least 24 hours after intercourse before observing cervical mucus.
- Certain medications: Some medications, such as antihistamines, may dry out cervical mucus, making it difficult to observe changes in consistency and amount. This is less common with more modern anti-histamines.
- Lubricants: Certain lubricants can mix with cervical mucus, making it difficult to observe changes in consistency and amount. It is best to use no lubricant at all when trying to conceive.
- Infections: Infections, such as yeast infections or bacterial vaginosis, can change the consistency, amount, colour and odour of cervical mucus, making it difficult to identify changes during the menstrual cycle. If any different is noticed to cervical and the change is also accompanied by pain, itching or discomfort, seek medical attention to treat potential infection.
It is important to note that while these factors can interfere with cervical mucus interpretation, they do not necessarily mean that a woman is not fertile, in fact, when using fertility awareness methods, the recommendation is to treat these interferences as “potentially fertile.”
Can I get pregnant on my period?
It is difficult to feel and observe cervical mucous during the menstrual bleed and so fertility during menstruation is “unknown.” Just because cervical mucous can’t be observed during a bleed does not mean that it not present. Many women assume that it is not possible to get pregnant while on their period, but in fact, it IS possible. Sperm can survive up to 5 days and so depending on how soon a woman ovulates, it is possible to have sex on your period and get pregnant a few days later during ovulation. In women with regular menstrual cycles, this is unlikely, but it can occur in women with short menstrual cycles and early ovulation. This becomes more likely during perimenopause when estrogen levels can sometimes fluctuate so high that ovulation occurs much earlier than usual.
Inter-menstrual Bleeding and Fertility
It is also not uncommon for women to bleed without a true period. A true period always follows ovulation, but other types of bleeding can occur. Any bleeding that is not a true period is called “inter-menstrual bleeding” and can range from some light spotting to heavy flow that goes on for days. In fertility awareness methods, any bleeding is considered as potentially fertile, and in fact, inter-menstrual bleeding often occurs with ovulation itself and is considered a highly fertile time. To identify wether a bleed is a true period or inter-menstrual bleeding, it is important to learn to chart the menstrual cycle and learn how to identify ovulation. When using FAM, all bleeding should be charted and treated as potentially fertile.
If you are interested in learning Fertility Awareness Method with an instructor, feel free to book an appointment with me.
References:
Curlin, M., & Bursac, D. (2013). Cervical mucus: from biochemical structure to clinical implications. Frontiers in bioscience (Scholar edition), 5(2), 507–515. https://doi.org/10.2741/s386
Najmabadi, S., Schliep, K. C., Simonsen, S. E., Porucznik, C. A., Egger, M. J., & Stanford, J. B. (2021). Cervical mucus patterns and the fertile window in women without known subfertility: a pooled analysis of three cohorts. Human reproduction (Oxford, England), 36(7), 1784–1795. https://doi.org/10.1093/humrep/deab049
Billings E. L. (1991). The simplicity of the Ovulation Method and its application in various circumstances. Acta Europaea fertilitatis, 22(1), 33–36.
