Cervical mucus is a secretion produced by the cervix that serves to prevent bacteria and viruses from entering the uterus. It also helps to increase lubrication, and to protect sperm from the acidic environment in the vagina. The presence of cervical mucus is important for sperm to reach the uterus during the fertile period.

Cervical mucus is a natural discharge that is normally noted on your underwear or when wiping. It is typically clear, white or slightly yellow, and is odorless. These characteristics may vary throughout the menstrual cycle and during pregnancy.

If you notice your vaginal discharge has a different color, a foul odor, or is thicker or has a different consistency than usual, it may indicate the presence of a health condition that requires assessment and possible treatment. Learn more about what different discharge colors can mean.

What it looks like

Cervical mucus will vary depending on the phase of your menstrual cycle:

1. Start of menstrual cycle

The start of your menstrual cycle is defined as the first day of your period. The estrogen and progesterone hormones that regulate your menstrual cycle are low during this time, and therefore cervical mucus production is low. This phase lasts for about 1 to 5 days, and any discharge is more difficult to visualize.

2. Following menstruation

Following menstruation, which is about the 6th or 9th day of the menstrual cycle, estrogen levels start to increase. However cervical mucus production remains low and the vagina is noted to be drier during this phase.

3. Fertile period

The fertile period is a series of about 6 days that surround the ovulation day. It generally starts between the 10th and 14th day of the menstrual cycle. Learn more about how to calculate your ovulation day.

At the beginning of this phase, there is a gradual increase in estrogen levels and cervical mucus production. This discharge will appear thicker, stickier and whiter. On ovulation days, the vagina becomes more moist and cervical mucus will appear shinier, more transparent and elastic, similar to egg whites. It is usually a sign that you are fertile. Read more about egg white discharge and other symptoms associated with it.

Cervical mucus during the fertile period serves to lubricate the vagina to aid sperm cells with entering the vaginal canal to reach the egg for fertilization.

Some women will analyze their cervical mucus to track their fertile window. This is known as the Billings method. Check out other ways you can calculate your fertile window.

4. After ovulation

Following the fertile window, progesterone levels start to increase a. This hormone prepares the uterus for possible pregnancy. Estrogen also start to decrease during this time. Cervical mucus production slows down, and discharge appears stickier or thicker. It may also appear to be pink in color as you approach your period. Read more about pink discharge after ovulation.

5. Menopause

Menopause is characterized by the end of the woman’s reproductive phase. It occurs when the ovaries stop producing estrogen, which results in a decreased production of cervical mucus. The vagina will become drier, and mucus can become thicker and with a different odor. If these symptoms emerge, you should see your doctor or gynecologist for assessment, as hormonal therapy and other treatments may be good options.

Cervical mucus during pregnancy

Cervical mucus is thicker and whiter during pregnancy due to normal hormonal changes that occur. Mucus serves to form a barrier to the uterus to protect it from bacteria and other microorganisms from developing, which can cause pregnancy complications. See what white discharge during pregnancy can mean.

Post-partum cervical mucus

After delivery, the body naturally eliminates residual blood, mucus and placental tissue for about 3 to 6 weeks. The uterus continues to contract back to its normal size.

During this phase, vaginal mucus will appear mostly bloody in the first days, and start to become browner with blood streaks by the 3rd to 10th days. After the 10th day, discharge will appear more yellow or white.

It is important to be monitored by your obstetrician or family doctor during the post-partum phase to ensure a speedy recovery.

How to assess

To assess cervical mucus, remove your clothing and insert a clean index finger into the vagina. Then remove the finger, and observe the quantity and consistency of the discharge. To become pregnant, cervical mucus should be plenty and it should be elastic in consistency.

Assessing your cervical mucus will not be accurate if you are using contraceptives, as the mucus can vary along the cycle, making it difficult to assess accurately.

Possible abnormalities

Women with difficulty getting pregnant may notice that their cervical mucus is thick throughout their entire cycle. This can interfere with sperm cell movement. Fertility problems should be evaluated by a gynecologist so that appropriate treatment can be initiated.

Cervical mucus may also be thicker when using contraceptives, as they interfere with normal ovulation and cause changes to normal hormone levels.

Changes to bacterial flora in the vagina and sexually transmitted infections can also cause changes to the color, quantity and odor of cervical mucus. These types of changes should also be assessed by a doctor to rule out illness.