Labor and Delivery Print The Role of the Mucus Plug in Pregnancy and Labor Medically reviewed by facebook linkedin instagram Medically reviewed by Anita Sadaty, MD on August 05, 2016 Anita Sadaty, MD, is a board-certified obstetrician-gynecologist at North Shore University Hospital and founder of Redefining Health Medical. Learn about our Medical Review Board Anita Sadaty, MD Written by twitter linkedin Written by Robin Elise Weiss, PhD, MPH Robin Elise Weiss, PhD, MPH is a professor, author, childbirth and postpartum educator, certified doula, and lactation counselor. Learn about our editorial policy Robin Elise Weiss, PhD, MPH Updated on September 30, 2019 Dorling Kindersley / Getty Images More in Labor and Delivery Pain Relief C-Sections If the word "mucus" makes you squeamish, you're not alone. But believe it or not, mucus and the mucus plug are important in conception and pregnancy. Mucus is produced during ovulation to help sperm pass through the cervix and provide them with an ideal environment before fertilizing an egg. Once fertilization occurs, the mucus changes to seal the cervix—with what we call the mucus plug—and protect the fetus from infection. Without the mucus plug, maintaining a pregnancy to term would be unlikely and, in some cases, impossible. How the Mucus Plug Is Formed The mucus plug is formed from secretions of cervical glands and has a thick, gelatinous consistency. The plug begins to form when the fertilized egg implants in the wall of the uterus. When this happens, the cervix softens and swells as mucosal cells start pumping mucus into the cavity until there are no gaps left. Prompted by the hormone progesterone, the mucus thickens and continues to be secreted throughout pregnancy, so that the plug always remains fresh. Within this thick, sticky fluid are antibodies that can protect the growing fetus from many bacteria, viruses, and other disease-causing agents. The mucus plug is roughly the size of a quarter and made up of around two tablespoons of mucus. It is generally a creamy to yellowish-white color and may sometimes be streaked with pink. It can also sometimes be more beige, or even brown, in color. This is not unusual and shouldn’t cause concern. How Cervical Mucus Changes Throughout Pregnancy The Role of the Mucus Plug During Labor Before labor begins, the balance of a woman’s hormones starts to change. Estrogen levels rise as the process of fetal development nears completion. As a result, the plug starts to thin and the cervix gradually softens and dilates. During this time, there may some discharge (which is typically odorless), or the plug may come out all at once. There may also be streaks of red or pink caused by the rupture of capillaries, which is why the loss of the mucus plug is sometimes referred to as the "bloody show." The passing of the plug indicates that labor is nearing, regardless of the stage of pregnancy. Therefore, if the mucus plug is passed during early pregnancy, it may be the sign of impending preterm birth. Passing the Mucus Plug It is impossible to predict when the mucus plug will be passed as it varies from woman to woman and pregnancy to pregnancy. In many cases, the passing will be evidenced by pieces of mucus found in the woman’s panties or bedsheets. Some women may not even notice it at all, because it was passed during urination or while showering. There is typically little, if any, pain when the mucus plug is passed. Some women will complain of nagging pain in the lower abdomen similar to menstrual cramping, though this is less common. When the plug is passed, it doesn’t necessarily mean that labor is imminent. At times, labor may begin in a few hours; at others, it may take several weeks. When the mucus plug is passed, it is usually a good idea to see your doctor or midwife to ensure that everything is OK and to give you a better idea of when you can expect to deliver. You'll also want to watch for known symptoms of imminent labor, such as lightening (when the baby drops lower into the pelvis), the beginning of regular contractions, and when your water breaks. Losing your mucus plug also doesn’t mean that your baby is suddenly at increased risk of infection. By this stage in the pregnancy, the amniotic fluids in the gestational sac offer ample protection right up until the time your water breaks. 7 Ways to Tell You're in Labor A Word From Verywell Once you have lost your mucus plug, you do not need to make any special accommodations, such as avoiding sex or baths. It is only when your water breaks that your baby starts becoming at risk of infection. However, if the passing of the plug is accompanied by heavy bleeding or a deep red discharge, call your doctor immediately, as these can be a sign of potential complications. Was this page helpful? Thanks for your feedback! Get diet and wellness tips to help your kids stay healthy and happy. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. American Pregnancy Association. Mucus Plug: Bloody Show. Aug. 2015. Becher N, Adams-Waldorf K, Hein M, Uldbjerg N. The cervical mucus plug: Structured review of the literature. Acta Obstet Gynecol Scand. 2009;88(5):502-13. doi:10.1080/00016340902852898. Continue Reading