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Discussion Starter · #1 ·
So here is a rather technical question for those of you who are pros:

I want to know how effacement, cervical dilation, and descend of the baby coincide on a time level.

I know there are stations. at 0 the baby has fully descended into the pelvis, is that correct? I am aware that every birth is a little different and it is not possible to give an exact time model of how everything happens. basically what I want to know is the order of things. once the baby is at 0 station, is what comes next the birth canal? does the baby have to pass the cervix to enter the birth canal? at which point is the cervix usually fully dilated?
I've been trying to get this straight with research in my labor progress handbook and some other books, but I can't seem to find the right section to answer my question.

Now, the reason I'm asking: with DS I was fully dilated but he never passed the cervix/couldn't be born, bc he was a brow presentation. In this pg I am attending a pregnancy yoga class and the teacher did a birthing meditation with us in which he *talked* us through the birth. ...only things sounded really wrong! basically he said that while the baby went from 0 to +3 the cervix slowly dilated and only when the baby 's head touched the pelvic floor the cervix was fully dilated. that's wrong, isn't it? I just couldn'T get into the whole relaxing and welcoming my baby mood with these instructions... I even went to talk to him after class to clarify this, but he was convinced that this was how it happened - and suddenly I was unsure (he has been giving those classes for 20 years now - I guess noone has challenged him on the details before... he said some other stuff that I know to be wrong, but I wanted to get this straight before next class).

Really curious about your answers!
 

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Sounds like he has been teaching it wrong for 20yrs. But it may be that there is some confusion about the term 'station'...at least HE may confused about 'station', even if he has the general steps/stages correct in his summation within the birth meditation.

'Station' to me refers to the position/descent of baby's presenting part relative to the pelvic outlet. The pelvic outlet is the lower opening of the pelvis defined by pubis symphisis and tailbone from mom's front to back, and by the ischial spines from side to side. The 'inlet' is the upper part of mom's pelvis, the widest part of her bony pelvic structure--the baby first comes into the inlet, and must turn/wiggle down into the outlet, the smaller and more distinctly defined opening at the 'bottom' of the pelvis (the lowest aspects of bony pelvis when mom is standing). Drawings of this can be found in many a birth related book and website.

As I understand it, at 0 station, the presenting part of the baby is at a level with mom's ischial spines; this is called 'engagement' in the pelvic outlet. This can occur at any time, from no dilation to full dilation. *Typically*, but far from *always*, the cervix dilates in a sort of correlation to baby's descent through the pelvis. That is, as baby slowly descends to +1 station-which means now baby's presenting part is 1 cm past ischial spines--fuller dilation occurs. But again, I've seen lots of moms get fully dilated even before baby is engaged/'0-station'.

There is a prevailing and at times powerful myth that it is the pressure of baby's presenting part on the cervix that causes dilation, but it is a myth! It is true in some births that dilation is slow until baby is at least at 0 station, where you are going to get some significant pressure on the cervix--and at this point, you are also very likely to be having stronger, longer contrax than before--the kind of contrax that get more birthing work done, faster.

Anyway, I'd be a bit concerned if a baby was coming past +1 to +2 and +3 without a great deal of dilation already done. At those more advanced stations, with a cervix at less than 7-ish cms, there could be significant hyperstretching of the cervix over the baby's head that can make it nearly impossible for the cervix to relax. This can be quite painful for the mom when this happens--I've used knee-chest position to help baby *back off* to a lower station, thus taking the pressure off a less-dilated cervix and allowing it to respond more easily to contrax in melting back/dilating more.

It is however true enough in my experience that once baby hits +3, if there is either full dilation, or at least 7-8cms with a loose, stretchy cervical rim remaining, then pushing can commence and it would be hard to avoid for most moms. Once baby's head is on the pelvic floor, there is usually a significant urge to push.

But again, I've seen baby's at +2 or more, with little dilation and this is a problem to adress.

Also, it is possible (though unusual for sure) that baby descends even to the point of being slightly visible, with a fairly closed cervix still covering the presenting part. This is definitely a problem!

There is really no strict, standard timeline/correlation between station and dilation--still, most often, dilation from closed to fully open occurs AS baby is moving into 0 station, and through to +1 and +2. And most often, with baby at +3, you have a mom who is fully dilated and feeling a strong urge to push because with baby on the pelvic floor, that's when fetal ejection reflex is stimulated strongly for most.

In any event, your guy has it wrong and doesn't realize it. It could just be a confusion of terms between you--he is a man and a yoga instructor after all, not someone I would count on for deep knowledge of maternity matters.


If you like the class and could find the meditation helpful, maybe you can allow that the instructor has the basic sequence of events about right, even if his terminology isn't technically correct.
 

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Discussion Starter · #3 ·
thanks so much for that detailled answer! I think I understand the process much better now. I'll have to read through it a few more times, but you've been tremendously helpful
 

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Quote:

Originally Posted by franjapany View Post
Now, the reason I'm asking: with DS I was fully dilated but he never passed the cervix/couldn't be born, bc he was a brow presentation. In this pg I am attending a pregnancy yoga class and the teacher did a birthing meditation with us in which he *talked* us through the birth. ...only things sounded really wrong! basically he said that while the baby went from 0 to +3 the cervix slowly dilated and only when the baby 's head touched the pelvic floor the cervix was fully dilated. that's wrong, isn't it? I just couldn'T get into the whole relaxing and welcoming my baby mood with these instructions... I even went to talk to him after class to clarify this, but he was convinced that this was how it happened - and suddenly I was unsure (he has been giving those classes for 20 years now - I guess noone has challenged him on the details before... he said some other stuff that I know to be wrong, but I wanted to get this straight before next class).

Really curious about your answers!
Not a midwife, but when I was sectioned, I had been fully dilated for many hours and pushed the baby's head past my cervix - she was at 0 station.
 
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