The production of vaginal secretions is a normal bodily function in a woman. The cervix produces clear mucus that sheds from the vagina along with cells to maintain vaginal health. A significant change in appearance, frequency or odor of vaginal secretions can indicate that something is wrong. If a woman's discharge is normally clear and becomes whitish or yellowish a visit to a medical care provider is needed.
The cervix produces clear mucus but when these secretions get exposed to air they can turn white or yellow explains the National Institutes of Health. The color change can also occur throughout the month, such as becoming clearer or more white in appearance during ovulation. These changes in vaginal secretions are most likely normal if they if they are odorless.
A bacterial infection, called bacterial vaginosis, can cause discharge that has an abnormal color like white, yellow or even gray. This type of infection will also cause a fishy odor that increases after sexual intercourse. The American Congress of Obstetricians and Gynecologists points out that common causes of bacterial vaginosis include antibiotic use, douching and spermicides. Some sexually transmitted infections, such as chlamydia, can cause a change in vaginal secretions including color, volume and odor.
A yeast infection occurs when naturally occurring yeast becomes overgrown in the vagina. This results in thick, white discharge that has a mild odor or no odor at all. When exposed to air the discharge often looks yellow.
When foreign substances enter the vagina the body's natural response is to produce secretions to cleanse the vagina. The woman's secretions mixed with the foreign substance can appear yellow or white. Some common causes of this type of cleansing discharge include semen, spermicides, latex condoms and harsh soaps. As with other causes of vaginal discharge, when the secretions dry, they may appear yellow in a woman's undergarments reports DermNetNZ.org.