What It Does
According to the American Pregnancy Association, a mucus plug is a thick layer of mucus that blocks the opening to the cervix during pregnancy. The mucus plug acts as a barrier to keep bacteria out of the uterus. The plug is expelled prior to labor. This expulsion is also referred to as "bloody show."
How It Is Released
The release of the mucus plug is a sign that the cervix is dilating and labor is approaching. The cervix thins and dilates as labor approaches, meaning the cervical opening becomes larger. At this point the mucus plug is no longer wide enough to fill the opening and falls out through the vagina. The mucus plug may fall out all at once, or gradually as the cervix will often thin over time. It is normally released as a clear, pink, or blood tinged jelly-like discharge. Some women will not notice that the mucus plug has fallen out and may confuse it with normal vaginal discharge related to pregnancy.
What It Means
Losing your mucus plug means that labor can be anywhere from a few hours to a few weeks away. The amniotic sac, the fluid-filled sac that holds the baby, is still sealed until your water breaks so the fluid will be protected from bacteria. There is no need to contact a doctor if the plug is normal in color and consistency. If the plug is bright red or more than an ounce contact a physician. This could be a sign of placenta previa or other pregnancy related complication.