Labor: Why is Ten Centimeters the "Magic" Number?

I would be grateful if you could explain to me why 10 cm dilation is so important. I know several women who wanted to push but weren't allowed to because the weren't 10 cm yet. I was told to push because I was at 10 cm but I refused as my baby wasn't in any distress. I started pushing 10 minutes later! It seems so strange that so many different sized women and babies all have the same criteria for pushing!


Peg Plumbo CNM

Peg Plumbo has been a certified nurse-midwife (CNM) since 1976. She has assisted at over 1,000 births and currently teaches in the... Read more

I once had a teacher who said the cervix actually dilates to 13 cm but 10 was a better number so we use that. You are so right about the "non-magicness" of ten cm dilatation. For one thing, it is very subjective. Just ask two providers to check the same woman. After four cm, the discrepancy gets higher and higher as labor progresses, then gets better toward the end of first stage. At this point, they are judging how many cm there are left.

I know some midwives who try not to check women in labor when they first feel the urge to push. They are waiting for the woman herself to tell them when they are completely dilated. And just because a woman is "complete" does not mean she is ready to push. Rotation of the baby, psychological and emotional status of the mother, position of the mother - all have a part to play in "readiness."

If all is going well and there is no indication for haste, it is best to let the mother push when and if she wants to. She will generally start with some tiny pushes at the peak of a contraction but as readiness is reached, the sensation becomes overwhelming and she will push more forcefully as the baby comes down. This type of "physiologic pushing", while the mother exhales as she pushes, is best for the mother and for the baby. It keeps the mother from becoming exhausted and keeps the baby's oxygen levels up.

If the mother does not wish to push, it could be that the baby needs time to rotate to a more favorable birth position. Sitting the mother up or getting into a squatting position or on all fours can facilitate rotation and mother's pushing efforts.

The danger with pushing too early is that the cervix becomes edematous and thicker, thus impeding progress rather than facilitating it. An early urge to push can sometimes be relieved my maternal position changes or by medication in labor.

I hope we have left the days when care providers proclaim a mother to be 10 cm and have her take in a lungful of air, grab hold of her knees and push for 10 seconds and repeat. I don't know of any other biological process where people require such "coaching". Surely there would be a lot fewer babies conceived if couples needed such encouragement during the mating.

This is one of the reasons why midwives are so good at what they do. They take their cues from the woman and her family and believe in and try their best to protect the normalcy of labor and birth.

So, you can tell that I very much agree with you.

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