Cervical Mucus: A Marker for Ovulation and a Must for Pregnancy?

For many of us, there is nothing more off-putting than the thought of tracking your cervical mucus day after day, month after month. It’s not easy knowing what you are looking at, why you are staring at your underwear, how long this exercise needs to go on, and what you will do with this information.

Egg white versus watery, creamy versus sticky. Are we baking a cake or making a baby? While in many ways, it’s sort of a little bit of both, tracking your cervical mucus is not a prerequisite for detecting ovulation or having a baby. The changes that occur over the course of those approximately 26 to 36 days can provide helpful hints on both if and when you are ovulating. However, while it is important and does serve as a reservoir for sperm, it is much lower on the fertility pecking order.

The cervix is the lower part of the uterus (a.k.a. the womb); it is the conduit between the uterus and the vagina. When not pregnant, the cervix measures about 2 to 3 cm. During pregnancy and particularly as its end is near, the cervix begins to shorten, thin out, and ultimately dilate. Think of the cervical mucus as the pond at the base of this conduit. It serves as a reservoir for sperm by providing it with nutrients and safety for several days (up to five, to be exact!). While the majority of sperm is in the tubes minutes after ejaculation, the pond holds on to the stragglers. Over the course of about three to five days, sperm is released into the uterus and the tubes, hoping to meet its mate and make an embryo.

Much like the variability in the uterine lining during the approximately one-month-long menstrual cycle, the cervix and its mucus also go through a host of changes. After bleeding has stopped, the cervical mucus is usually scant, cloudy, and sticky. This lasts for about 3–5 days. What comes next is the stuff that you are taught to look for.

In the three to four days leading up to and after ovulation, the mucus changes to clear, stretchy, and fairly abundant. Following ovulation, the cervix becomes somewhat quiet, and cervical discharge remains scant. The “stage hands” behind the curtain setting the scene for the changes observed in cervical mucus are estrogen and progesterone production. Altering levels of estrogen and progesterone results in major modifications in mucus content and production.

If the cervix falls short on producing and maintaining its reservoir (a.k.a. mucus), problems can arise. However, while cervical factor infertility used to be considered a serious and real problem, today the cervix and cervical mucus production are hardly ever the cause of infertility (only about 3% of infertility cases are due to the cervix). Because of this, tests to evaluate the cervix/mucus are no longer needed.

Traditionally, a postcoital test (nicknamed the PCT) was performed to seek out cervical dysfunction. Now, picture this: fertility doctors used to obtain a sample of cervical mucus before ovulation and after intercourse and check it out under the microscope. They were looking for the presence (or absence) of moving sperm. Although this is sometimes used in couples that cannot have a formal sperm check, it is otherwise one for the ages. The subjectivity, poor reproducibility, and very inconvenient aspect of it have eighty-sixed the PCT in the land of fertility medicine.

In cases where the cervix has been previously cut, burned, or frozen, a narrowing of the cervical canal can arise (medically called cervical stenosis). Cervical stenosis can make procedures that require access to the uterus difficult (picture trying to pass something through a really narrow hole—it doesn’t fit!). Therefore, prior to undergoing any fertility treatment, a cervical dilation (that is, a widening of the cervix) may be required. This allows your doctor to then put sperm or embryos back into the uterus.

However, while the narrowing can make infertility procedures somewhat more challenging, the width is not what’s causing the entire problem. Cervices that have been exposed to trauma like surgery can have difficulty producing mucus. No mucus equals not much of a place for the sperm to hang out (cue IUI or IVF).

While the cervix may not be playing the feature role in the fertility play, it does serve as an important role. In addition to providing a respite to sperm, it also helps maintain a pregnancy to term. When a cervix shortens or dilates before time’s up, it can lead to a snowball of negative events: preterm labor and preterm delivery, to name a few. Bottom line, it’s not only a reservoir but also a roadblock. Until that nine-month mark has passed, it should not let anything out that front door!

Think about your cervix and cervical mucus but don’t drive yourself nuts. Yes it is a way to confirm ovulation but no it’s not the only way. While we are advocates of knowing your body and being aware of what’s going on with your cycle, obsessing over what’s going on won’t change what’s coming out. We have ways to get the sperm to meet the egg even if the cervix isn’t cooperating!