The cervix, which is the lower, narrow part of the uterus, secretes a substance called cervical fluid. During a woman's monthly cycle, the cervix produces this fertile fluid that acts as both a lubricant and an agent to nourish and help sperm move from the vagina and cervix to the uterus. Throughout the range of a woman's monthly cycle there are changes in amount, color and quality of the cervical fluid, also known as cervical mucus. This change goes hand in hand with the time of the month when a woman is ovulating and, thereby, most fertile.
After a woman's monthly menstruation has ceased, there is period of three to five days when there is an absence of or only a very slight amount of cervical fluid. Any fluid that may exist will be clear or slightly white. This time period is considered an infertile phase of the monthly cycle.
In the next phase of the cycle, which typically lasts for two or three days, the cervical mucus becomes sticky. Although there is actual fluid, it still has a dry and tacky quality and is white or creamy in color. This period, although considered an infertile period, is a movement toward ovulation, and there is a slight chance of pregnancy.
Moving into the fertile time period, the cervical fluid becomes more abundant and milky in nature and the woman will now have a feeling of vaginal wetness until menstruation commences. The mucus may be creamy and thick or smooth. The color of the fluid is either yellow or white. This stretch lasts from two to four days.
The most obvious sign of fertility is when the cervical fluid takes on the consistency of egg whites. This change in mucus comes right before and during ovulation, and it is during this time that there is the greatest amount of fluid. Sperm have the highest chance of survival during this time.
The cervical fluid changes in amount and quality after ovulation. At this point in a woman's cycle the mucus varies from woman to woman. It may be watery and moist or dry and sticky. The fluid will stay like this until the end of the monthly cycle, which is the day before menstruation begins. The mucus may be colorless or white and the woman has a dry vaginal feeling.
If a woman is interested in examining her cervical fluid for fertility purposes, she can collect this fluid in a couple different ways. She can use toilet paper to wipe the entrance of the vagina. She may also collect cervical mucus by inserting a finger into her vagina and extracting some fluid. This method is preferable because it will allow the woman to check the actual cervical mucus as opposed to just the wetness on the toilet paper. The attributes of cervical fluid may indicate when pregnancy seems likely or unlikely but, to be more certain of avoiding pregnancy — if that is the woman's wish — then she should use some form of birth control.