It is obvious that the uterus undergoes many changes during pregnancy; most visibly, it increases in size and changes shape. The hormones of pregnancy also cause changes in the cervix preparing it to hold and protect the fetus and eventually dilate for birth.
Before conceiving, if a woman checks her cervical position and texture with her finger daily, she will be familiar with the changes typical for her throughout her menstrual cycle. She may notice changes in her cervix during her pregnancy if she has her pre-pregnancy baseline to compare it to.
To visualize a non-pregnant cervix, imagine a pink cylinder with walls about a centimeter thick and a very narrow inner passageway that connects the body of the uterus to the vagina; the end of the cylinder protrudes into the vagina about an inch. The cervix of a woman who has already had children may be a little larger in all dimensions.
Due to rising levels of estrogens during pregnancy, more blood flows to the pelvic area and the cervix often feels softer or more velvety to the touch. The cervix also usually thickens in width and it may rise up higher into the vagina. However, the timing of this softening varies from woman to woman – some experiencing it shortly after their missed period and some not until a few weeks or months after pregnancy has been confirmed. In this way, it is usually not a reliable indicator of pregnancy – instead taking a urine or blood test is recommended.
The glands inside the cervical canal (the inside of the cylinder) secrete fluid and mucous throughout the menstrual cycle. These same glands proliferate and produce a thicker type of mucous under the influence of pregnancy hormones. This creates the infamous ‘mucous plug’ that rests in the cervical canal protecting the fetus and uterus from infection during pregnancy. This gelatinous yellow, clear or pink-tinged plug begins to dislodge and may come out in late pregnancy or in labor, often called ‘show.’ Another type of glands in the cervical canal are also activated to secrete more fluid in pregnancy, often causing a rise in watery or creamy vaginal discharge.
In some pregnant women, the cervix may appear blue or lilac colored also due to increased blood supply to the cervix. Of course, this is only visible upon speculum exam, which most women don’t do themselves and many are advised not to during pregnancy.
As the birth approaches, the length of the cervix begins to thin (called effacement), though this happens at different times for different women, sometimes weeks beforehand and sometimes during labor. She may feel twinges in her cervix as it continues to soften in this way.
Individual circumstances will affect how and when the cervix changes in each pregnancy. If you’ve got questions or concerns about your cervix, don’t hesitate to call your doctor or midwife!