Understanding mucus plug
What does it look like
The mucous plug is a collection of mucous inside the cervical canal that act as a barrier to the cervix, known as the cervical os. It is worth noting that these secretory cells are controlled by progesterone, a key hormone in pregnancy. The mucous plug is a physical defence mechanism with the additional function of stopping viral proliferation to protect the foetus.1
Can mucus plug be clear
The mucus plug is formed mainly of high molecular weight glycoproteins, formed of a core of protein with attached carbohydrates in the form of a web. The pores in this web become larger in non-pregnant people to allow sperm passage than in pregnant people when the pores become narrow. Thus, clarity of the mucous plug is hormone dependent due to its mucin component that diminishes its clarity with the higher density in the pregnancy status, rather than the lower density of the non-pregnant fertile person or in menopause.2
Causes of losing the mucus plug
The normal bacterial flora (commensal organisms) that live in the vagina also contribute to the components of this elastic mucous plug, rendering it at an acidic pH that is hostile to many viruses and microorganisms. As a result, any disturbance in this bacterial flora will affect the defensive nature and composition of the plug. This condition can, unfortunately, happen during excessive vaginal douching. Moreover, it may happen as an exposure to excessive pressure that could dismantle the cells in the vaginal wall to which the plug is attached. The pressure could be from inside in the case of labour or outside in the case of trauma.3
How to know when it is cleared
The mucous plug is a companion for the female genital tract during pregnancy, so its clearance may be accompanied by the following signs of disturbance or termination of pregnancy:
- The appearance of signs of infection in the baby may appear on ultrasonography as turbid amniotic fluid.
- Fall of blood from the woman or fetal parts in case of abortion.
- The appearance of the show (some of the amniotic fluid around the baby) on labour.
- Change of the acidity of the vaginal tract as well as the appearance of profuse secretions.
What to do after losing mucus plug
The loss of the mucous plug means a loss of cervical protection for the baby, with a higher possibility of intrauterine infection. This raises the probability of preterm labour if the pregnancy is still before 37 weeks or term labour if the pregnancy is over 37 weeks. In the case of preterm labour, continuous monitoring of the baby's vital signs is a must through a medical team consultation. In addition, a decision on labour enhancement should be taken in order to guarantee the safety of the foetus and the mother. Injection of steroids should be done within 48 hours to aid in the maturity of the baby's lungs. In the case of term labour, nothing is to be done other than monitoring the vital signs of the baby by a medical team since the mother is in the labour state of a mature baby.4
When to seek medical attention
Medical attention is essential for premature labour due to the high mortality rate of mothers with subsequent intra-uterine infections following the loss of the mucous plug. The possibility of these infections increases with the prematurity (earliness) of the labour before 37 weeks as well as leads to premature labour. It is believed that the ascent of infections in the female genital tract stimulates uterine contractions to expel the invading organisms. To sum up, the appearance of the show (amniotic fluid) or blood in a pregnant woman indicates the loss of the mucous plug, which requires medical supervision for labour preparation and ensures the safety of both the mother and the fetus.
Finally, the mucous plug appears to be the safety button for both the mother and the baby. Its clearance shows several alarming signs that we should observe to avoid any further complications.
- 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.
- Chrétien FC. Ultrastructure and variations of human cervical mucus during pregnancy and the menopause. Acta Obstet Gynecol Scand. 1978;57(4):337–48.
- Lacroix G, Gouyer V, Gottrand F, Desseyn JL. The cervicovaginal mucus barrier. Int J Mol Sci [Internet]. 2020 Nov 4 [cited 2023 Jan 3];21(21):8266. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7663572/
- López Bernal A. Overview. Preterm labour: mechanisms and management. BMC Pregnancy Childbirth. 2007 Jun 1;7 Suppl 1(Suppl 1):S2.