Your cervix is not psychic. It IS circular, but that is where its similarities with a crystal ball end. The cervix may provide a hint of information, but it has been given far too much glory. Let me dethrone the dilation myth.
It has become mainstream practice to uncomfortably place your feet in stirrups, sport the paper gown and tissue blanket, and begin cervical exams as early as 36 weeks during OB visits. Because this is common practice (note I did not say evidence-based), women often ask to “be checked.” Typically, this is grounded in three motives.
- A family member or friend has been asking them how far along they are.
- They are heavily pregnant and tired, thus desiring a clue to when labor may begin.
- They subscribe to the myth that a cervical exam divulges significant secrets.
All three motives are unsubstantiated. The truth of the matter is a cervical exam is physically and mentally unpleasant for most. Although we can clinically detect dilation, effacement, and station, that triad provides little information about progress or labor.
Allow me to use my textbook voice for a moment.
Cervical dilation is the opening of the cervix (the doorway to the uterus). Measurement of dilation is on a scale from 0-10 centimeters. Zero being closed and ten being completely open. The cervix must open in order for a baby to be born vaginally.
Cervical effacement is described in percentage (0-100%). Effacement is the thinning of the cervix. Zero signifies no change in thickness while 100% is completely thinned out like a sheet of paper. A thin cervix is part of the recipe for a vaginal birth.
The term station causes a baby to sound like it’s a train. If that metaphor helps you remember context, let’s use it. Station doesn’t measure the cervix at all. Actually, your midwife is feeling how far your baby’s head has journeyed downwards into the pelvis (like a train traveling down). It is measured on a negative to positive scale (-4 to +4) depending on where the baby’s head is relative to the ischial spines of the pelvis. Plus four means we are about to welcome a baby earth-side while minus four means your baby is high and floating.
I have been in your shoes, a handful of times actually. Waiting to meet your bundle, filled with desire and hungry anticipation. You have prepared, and every detail has been taken care of. Your toenails are painted. Your legs are shaved (or not). The nursery is perfect. The car seat is buckled in and ready for precious cargo. Hasn’t this baby gotten the memo? You are ready! You are impatiently waiting for a sign from the heavens that labor will start, yet you are receiving nothing. No mucous. No contractions. No glorious breaking of the waters. A big fat zilch. That’s when the idea bubble appears…”Can I be checked?”
As a midwife, I covet the imaginary pin that could pop that bubble. All I am equipped with is information, and that information tells me there is no supportive evidence for routine cervical exams during the last weeks of pregnancy. The exam provides modest information, is invasive, and introduces some risks. The evidence exposes to us that numbers, rather percentages or centimeters, are not predictive by nature. They are not indicators of labor or timely progress. They are remedies to curiosity. I have witnessed women sitting at 3-4 cm for weeks, and I have seen a woman move from 4 cm to holding a baby in less than an hour. Furthermore, setting a woman up by way of believing her labor will start any day because she is dilated/effaced only to have nothing come to fruition is just as detrimental as the disheartening news of her cervix being closed.
Women are known to lose trust and confidence in the ability of their bodies when they feel nothing is happening. Those false messages based on how open her cervix is are loud and tell a woman that her body is not working as it should. Untrue. Your cervix is so amazing! It softens and stretches and thins and opens. It is quite a Jedi. But, Yoda would tell us “crystal ball, a cervix is not.” Depending on the cervix to predict your future could fill you with encouragement that could turn into despair. None of us know when your labor dance will begin. Including your cervix.