labor nurse has been reborn and shares her experiences as a new nurse-midwife, woman, and blogger

Saturday, July 21, 2007

ChildBirth Ed Terminology Part 2

The following is the second post in the Childbirth Education Series that was originally posted on Life & Times.

Childbirth Education, Terminology Part 2

So has everyone studied their terms from part one? Good, because you'll need to know it as we move along here.
Station: This refers to the location of the top of the baby's head in relation to the ischial spines within the pelvic cavity. Ok... what? Take a look at this:

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This is a pelvis with the front portion cut off (like the pubic bone) to reveal those ischial spines. So the top of the baby's head is assessed in relation to that in either a positive or negative number with zero being in line with the spines. So your nurse, midwife, or doctor says to you: "You're 5/100/0". This means you are 5 centimeters dilated, 100% effaced, and at zero station. A positive number, like +2 means that the top of baby's head is about 2 centimeters below the spines.
Vertex: Most people say vertex when they are talking about the baby's position, which in that case would mean head down. But it literally means the top of the baby's head. You might hear someone say, "The vertex is well engaged" or "The vertex is +1".
Placenta: Again, I am not trying to insult anyone here by putting placenta in the terminology, but would like to share some interesting facts. The placenta is the only organ a body will grow "from scratch" and get rid of without detrimental effects. The placenta is the important exchange organ between mother and fetus. It provides oxygen and nutrients to the fetus, and takes away waste products (like carbon dioxide) so that mom's body can get rid of it. There are two sides to a placenta: maternal and fetal. The vessels on mom's side and baby's side, in perfect circumstances, never come in to contact with each other. Instead they come very close to each other and diffuse their substances across to each other. Pretty cool, huh?

This is the fetal side in the picture. You can see the umbilical cord on the right upper corner.

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And this is the maternal side which was attached to the uterus. Makes you want some steak, huh?
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Placentas also produce hormones that support the pregnancy. For all those infertility mom's out there taking progesterone until you are between 7-12 weeks stop when the placenta is putting out the full amount of progesterone needed. The beginning stages of the placenta are what produces HCG, the hormone used to detect pregnancy.
Placentas act as a filter as well. This is why some medications are ok to take and some are not. Some medications do not cross the placenta, some do and it is not considered harmful to the fetus, some do and are harmful, and some drugs we just don't know for certain about anything. It is unethical to do random clinical trials/research on pregnant women when testing drugs. So this is why the answer to, "Is it ok to take such and such?" gets you the answer: "It is thought to be safe, but we don't know for certain."
Umbilical Cord: This is the line between mother and fetus. It contains two arteries and one vein and is protected by a jelly like substance called Wharton's Jelly. You'll notice when the baby is born that the umbilical stump right after birth is a moist off white-ish substance. The baby below is just born and shows the Wharton's jelly really well. And don't worry, we trim that way back so that no one can jump rope with it.
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Amniotic Sac and Fluid: Hang on to your seat because everyone falls off it when I tell them that the baby produces the amniotic fluid with its kidneys, pees it out, swallows it, and keeps making more. Ya, that's right. They are constantly recycling amniotic fluid. By full term healthy babies make and recycle about 1 liter of fluid. Keep in mind, however, that the baby is in a sterile environment and so it's not the same as if an adult was drinking their own piss.

Here you can see the placenta with the amniotic sac pulled out to demonstrate the baby's ex-home:

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The amniotic sac is a very thin yet strong membrane that keeps the fluid and baby well protected. The sac and fluid act as cushions and muffle any movement from you. It is said that those whose water breaks in a big gush have a tear very low in the amniotic sac whereas the slow trickle is from a tear high up in the sac.


ellen dee said...

I'm so glad to have found you again. I am glad you came back.

(Kori, L&D RN)

The Nurse said...

You need to publish this... is definitely not found in "What to Expect When You're Expecting." The author to that must be as wealthy as JKRowling!

Anonymous said...

I was under the impression that all medications passed through the placenta, but there were differences in the concentrations?

And especially as far as any medications that might be used during labor (narcotics, anaesthetics, pitocin, mag. sulfate, etc), that they all cross the placenta to a degree (some more than others).

But, you are saying that some medications don't cross at all?

I would love to learn more about that.


alisaterry said...

I appreciate the pictures of the placenta, since I was guilted into a c-section (I can't guarantee your baby won't be brain damaged!) and missed my placenta. I really wanted to see it.

Labor Nurse said...

the nurse, I am publishing it! Here on the blog, of course. Perhaps when the series is completed I could work on something there....BTW...I hate What to Expect.

Anonymous, you sent me off on a little research escapade to answer your question. I wanted to make sure I was giving the right info re: drugs crossing the placenta (or not crossing). So, what I found supports my original statement. In particular, drugs that have high molecular weight do not cross the placental easily or at all. An example in Lange's Basic & Clinical Pharmacology, 9th edition, states that heparin has such a high molecular weight that it does not cross the placenta at all. There is a whole lot more to this, so maybe you just opened a can of worms for me here... stay tuned.

alisaterry, glad to provide you with the pictures. Most placentas look about the same at term, so yours likely looked just like the ones here!

Sarah Stewart said...

Love the pictures of the placenta & that you've published them with CC license - we will be linking to them as part of the midwifery education second life project I am working in:

cheers Sarah