In a healthy menstrual cycle there is a gradual progression of changes in discharge and cervical mucus that determine when a woman is potentially fertile or not. It may take a little practice, but you can learn to identify your own stages of cervical mucus.

In order to confidently identify optimal times for conception, it is important to understand the role of cervical mucus, the various types of mucus you may experience, and what they mean for your fertility.

What is Cervical Mucus?

Cervical fluid, more often referred to as cervical mucus to differentiate it from the other types of fluids secreted through the vagina, is a hydrogel composed of water, mucus molecules, and biochemical compounds. The mucus is created in "crypts" which are tunnel-like channels within the cervical canal. Cervical mucus production is stimulated by the rise and fall of estrogen and progesterone secreted by the ovaries during the menstrual cycle.

To date at least half a dozen different types of mucus have been identified, with corresponding crypts, each serving a unique function. An ideal way to identify different types of cervical mucus is to separate them into two categories: somewhat fertile or non-peak mucus and peak mucus that is considered most fertile.

What Makes Cervical Mucus Fertile?

The reason cervical mucus is so crucial to fertility is that it changes the pH balance of the vagina from its natural acidic state to be more alkaline (basic) which is a necessary condition for sperm survival. Cervical mucus provides a fluid through which sperm can swim in order to get up into the fallopian tubes. Certain types of cervical mucus are responsible for trapping mutant sperm to prevent them from creating a non-viable pregnancy.

Cervical mucus also supports a process called capacitation, an enzymatic process that matures sperm and makes it possible for the acrosome reaction to occur, which is necessary for conception.

What Does Fertile Cervical Mucus Look Like?

All cervical mucus that can be finger-tested (when you can pick up mucus from the toilet paper or underwear and stretch it between your thumb and forefinger), is potentially fertile. In the presence of cervical mucus sperm can live up to five days. The most fertile mucus is associated with a lubricative or slippery sensation at the vulva, is clear, and has "spinnbarkeit" properties, meaning it can stretch like egg white.

This means that if cervical mucus has any one of the following qualities, it should be considered peak mucus (most fertile):

  • All mucus that is clear is peak
  • All mucus that stretches more than an inch is peak
  • All mucus that feels lubricative is peak

If cervical mucus has none of these qualities, it is considered non-peak.

(No Mucus)
Somewhat Fertile
(Non-Peak Mucus)
Most Fertile
(Peak Mucus)
ColorNoneWhite, CloudyClear
ConsistencyNo StretchStretchable to less than 1 inch, sticky, pasty, gummy, or tackyStretches more than 1 inch, or is watery

Identifying Stages of Cervical Mucus

Cervical Mucus and Ovulation

The last day that an individual produces peak mucus has been shown in research studies to be highly correlated with the day of ovulation. Ovulation may occur up to +2 or -2 days from this peak day. Three to seven days of peak mucus is considered normal.

Since sperm can live up to five days in the presence of peak mucus, intercourse and insemination do not have to be timed for peak day (and usually can't, since it is retroactively identified as the last day of peak mucus), but should be timed to coincide with alternate days throughout the time of fertile mucus, as well as the first day that peak mucus either dries up or turns into non-peak mucus (mucus not clear, stretchy (1" +) or lubicative).

Stages of Cervical Mucus

Individuals vary greatly in their pattern of cervical mucus production both in quantity and quality. In general, menstruation should be followed by 3-7 days of no mucus.

This should be followed by either immediate observations of peak-type mucus (clear or lubricative or stretching more than an inch) or by observations of white, sticky or pasty mucus for a day or two before the onset of peak-type mucus.

Peak-type mucus should be observed at least once a day for at least three days in a row, and up to seven days.

Following peak day and the confirmation of ovulation, mucus should dry up within three days and there should be no discernible mucus at the vulva until just prior to menstruation.

Cycle PhaseObservationTypical CycleNormal Cycle
Phase Length
MenstruationBleedingCycle Days 1-51-7 Days
Pre-Ovulation (Infertile)Dry (No mucus)Cycle Days 6-92-13 Days
Pre-Ovulation (Fertile)MucusCycle Days 10-143-7 Days
Ovulation Last Day of
Peak Mucus
Cycle Day 1424 Hours
Dry (No mucus)
Cycle Days 15-28
12-14 Days

What is White, Sticky or Pasty Cervical Mucus?

Mucus that is not clear, stretchy (1"+) or lubricative is called non-peak mucus and is characteristic of mild estrogenic stimulation of the cervix. It is normal to have a day or two of transition into fertile mucus that is marked by non-peak mucus that is cloudy, sticky or pasty.

Although non-peak mucus can be supportive of sperm survival, it is generally less supportive of conception than the peak mucus described above. If you experience this type of mucus throughout the latter half of your cycle, it can indicate a possible progesterone deficiency, as progesterone levels should rise enough to cause a mucus plug in the cervix- preventing any mucus from being observable at the vulva.

What Does Thick Cervical Mucus Mean?

Thick mucus that looks like a long glob, sometimes even dangling out of the vagina when going to the bathroom is healthy and normal. Thick mucus that is globular, yellow or looks like dried up glue is not healthy and is often a sign of inflammation. It can be a result of an acute inflammation due to environmental allergies, food sensitivities or an infection. If it persists further testing should be done to rule out cervicitis, allergies, or chemical irritations.