In women there are specific times at which the cervix, which opens to the uterus, may open or dilate. Most of the time it sits in a closed position, but certain surgeries can open the cervix to gain access to the uterus, and even some gynecological procedures can do this. Either medically or naturally, at the end of a pregnancy, a dilated cervix occurs to allow passage of the fetus out of the uterus.
Though people may associate a dilated or open cervix as something that occurs at the end of a nine-month pregnancy, it certainly can occur at other times. Both dilation and curettage (D &C) and dilation and evacuation (D & E) widen the cervix to get access to the uterus. There are many circumstances under which either of these procedures might take place — to cause an abortion, to end a missed miscarriage or to complete a miscarriage. A D & C may also occur to treat conditions like heavy vaginal bleeding or to check for cancer. It’s important to recall that a dilated cervix also occurs during miscarriage, though sometimes this needs to be induced if it is missed.
Some gynecological office procedures also depend on dilating the cervix to a certain degree. Placement of some birth control devices requires it, as in the case of hormonal or non-hormonal intrauterine device (IUD) placements. Typically, this short dilation can be slightly to very uncomfortable, even though the cervix may only be opened a centimeter or two.
In a normal pregnancy, the cervix remains mostly closed until the point of labor and delivery. In the last few weeks, Braxton-Hicks contractions may result in slight cervix dilation, and some women may pass a mucus plug called the bloody show that indicates labor is imminent. During the active and transitional phases of labor, the cervix continues to dilate, and measurements may be taken to determine its specific width. Full dilation is ten centimeters (3.94 inches). When this is reached, women are usually instructed to begin pushing.
Since cervical thinning or effacement is part of achieving the fully dilated cervix, many pregnant women want to know how they get to this point sooner. There are many tips and tricks for achieving some dilation when due date is reached. One of the best known of these is having intercourse with a partner. Exposure to sperm is exposure to prostaglandins, which aid in softening or effacing the cervix. With an induced labor, doctors may use a prostaglandins insert to achieve a softened or dilated cervix.
Achieving a dilated cervix faster is not always desirable. Some women quickly dilate in what is called precipitous labor. This may not be initially noticed or very painful, so that when labor signs do present, things are suddenly extremely painful and delivery moves at too fast a pace. Ultimately, gradual dilation, though uncomfortable, is usually safer for both mom and baby.