Mucus plug

...the mucus plug is just an accumulation of secretions that form within the opening to the uterus, also called the cervical canal. The fact that mucus accumulates early in pregnancy is quite beneficial, as it serves to create a protective barrier against infection between the outside world and your growing baby.As you near the end of your pregnancy, your cervix will begin to thin out and dilate. As it changes, you may lose your mucus plug and find a gooey deposit in your underwear or on the toilet tissue after wiping. It is not uncommon for this mucus to be mixed with brown, pink, or red streaks of blood from the changes occurring within your cervix. Some women may lose the plug at 36 weeks' gestation, while many others may not lose it until labor has begun.

This morning, Donna loses her mucus plug. I am eating toast. She says to me "I've saved it. I can show you if you like". I decline.

...loss of the mucus plug is often the first sign that labor is approaching. Before you make a mad dash to Labor and Delivery, however, remind yourself that many women do not go into labor for a week or two after this event.