Artificial Oxytocin Induction
The easy answer to a Pitocin or Syntocinon induction is even though it's an artificial induction with artificial oxytocin you would think "it's the same hormone, why not?" but it goes much deeper than that. First of all, I will explain what happens during natural labour vs. an induction or augmentation and then explain the risks involved.
When a woman goes into labour on her own, it is her baby who initiates labour. Thus when baby is "ready" prostaglandins are released which soften the cervix, preparing it for opening. Then the body releases oxytocin which is noticed when contractions start and they will strengthen, become longer and closer together as time goes on. If baby is finding it difficult labour will slow or even stop as in posterior presentations and long prodomal labours. Baby is using the contractions to help turn and get in a good position. With each contraction the long muscle bands running vertically (picture mom sitting upright on a birth ball) pull the cervix open as the strong mass of muscles at the top of the uterus push down. The horizontal muscles tighten, but just a bit, in order to make sure baby is aligned properly and help guide baby down. As labour progresses the mass of muscle at the fundus gets thicker because it is pulling the cervix up and away from the birth canal and the baby is moving lower. Then when transition hits and baby moves two or three stations quickly after the cervix is dilated, a lull in the contractions happens because the uterus has to "catch up" to the baby. When second stage or the pushing stage comes all the uterine muscles push and guide the baby through. Third stage the umbilical cord stops pulsating as the uterus clamps down because the muscles cross each other and as they contract they cut off the blood supply to the uterus and it sloughs off the uterine wall to be expelled.
OK now let's look at pit induction. A baby not yet ready for labour is slowly starting to feel contractions. That is OK because baby is used to uterine contractions throughout the pregnancy. They become stronger and baby is still fine, as he is guided down and uses his head to dilate the cervix. This may be a bit troublesome if the prostaglandins have not been able to soften the cervix prior to contractions, but with a good Bishops Score (see Bishops Score) this should not pose a significant problem. But what he notices is that it isn't only the longer muscles that are contracting, but also the horizontal ones, so he is not just pushed down, but squeezed hard from all sides. In artificial induction's the entire muscle contracts evenly, instead of just the fundal muscles pulling the cervix open. It is more difficult for baby because he isn't guided down as easily as would be in an uninduced birth. Contractions often are longer with less of a break between so baby has less time to recuperate between, and if he is posterior or asynclitic, it would be difficult to rotate or turn into a good angle, which is very common because baby isn't ready for birth yet. Regardless of this, induced births, once established, often go quicker because the uterus is working much harder than it would normally. The cervix will often dilate quicker and labour will be shorter. This can really distress a baby, especially if he has to mold quickly. If he is posterior a LOT of molding will occur in order for his head to fit.
Add to this the position an induced mother is in, almost always on her back in a semi-sitting position due to the continuous EFM (external fetal monitor) she needs to monitor her baby. This position often will turn an anterior and well positioned baby posterior as the baby tries to negotiate the pelvis that is compromised by this position.
The mother is also expected to not eat or drink during labour in case she needs a cesarean section which further compromises her bodies ability to birth. Picture working hard for several hours gardening or any physical labour where you are using large muscle groups. Then imagine not eating or drinking during this and how that will effect your ability to work. When a woman is in labour at full term her uterus is the largest muscle in the body and needs to work efficiently in order to open the cervix and push her baby out. When her uterus is not getting adequate nutrients or fluids lactic acid builds up which causes that sore and stiff feeling you get when you are working a new muscle group you have note used for a while. Women in general do not consume adequate fluids at the best of times and to have that compromised even further by withholding fluids just compounds the problem the blood has in transporting adequate oxygen to the uterus as it works and removing the carbon dioxide and other wastes from the cells as they use up energy.
To counteract this caregivers often give IV fluids, usually Ringers Lactate, to the labouring mother to provide adequate hydration and at the same time to administer the induction medications. What is ironic about this is the very fluids used to provide hydration, thin the blood and hence the very oxytocin that is given to produce contractions. So more induction medication is needed to produce the same result. Also because the blood is thinned it lessens the number of red blood cells that are needed to provide adequate nutrients to the hard working uterus. Finally, the endorphins that the body produces naturally in conjunction with it's release of oxytocin are not produced adequately because of the artificial method of administering the oxytocin, but at the same time, the endorphins are less effective because those that are produced are again thinned by the IV fluids.
At the l997 DONA conference, Marshall Klaus MD spoke about the difference in the mother's experience when she is producing a lot of her own oxytocin vs. when she's receiving oxytocin from outside her body. Endogenous oxytocin is produced in the pituitary gland in the brain, and although much of it goes out into the bloodstream and makes contractions, some of it stays in the brain and raises the woman's pain threshold. Pretty convenient system, as her body produces more contractions and they get more painful, her pain threshold rises. Artificial oxytocin - Pitocin or Syntocinon - goes in through a vein and can't cross the blood brain barrier, so the mom gets more pain without raising her pain threshold. Ouch! Now let's look at the risks…
"Dr. Caldeyro-Barcia concluded (after a collaborative study in twelve Latin American medical centers) that in oxytocic-induced labours, even with proper precautions--such as the lowest effective dosage given and proper monitoring of mothers--almost seventy-five percent of the mothers' uterine contractions were shown through fetal heart monitor tracings to result in a reduction of oxygen to the baby's brain." (Immaculate Deception, 1975)
"The mother should never be left alone while the oxytocin infusion is running. Uterine contractions must be evaluated continually and oxytocin shut off immediately if contractions exceed one minute in duration or if the fetal heart decelerates significantly the frequency, intensity, and duration of contractions, and uterine tone between contractions must note exceed those of normal spontaneous labour. Oxytocin is a powerful drug, and it has killed or maimed mothers through rupture of the uterus and even more babies through hypoxia from markedly hypertonic uterine contractions." (Williams Obstetrics)
"The Golan study concerned ninety-one cases of uterine rupture during a five-year period. Of these, 61 occurred in normal uteri while 32 were found in patients who had undergone a previous section. There were nine maternal deaths, and all occurred in the group of mothers who had not had previous cesarean surgery. The fetal mortality was also much worse for the women without previous cesareans. The fetal mortality for the previous cesarean group [who experienced uterine rupture] was twenty-two percent, while it was more than triple, or seventy-four percent, in the unscarred group [who experienced rupture]. The ruptured uteri in the normal, unscarred group were, for the most part, associated with oxytocin administered during labour." (Joy of Natural Childbirth, 1994)
Both the AOGC (American College of Obstetricians and Gynecologists) and the SOGC (Society of Obstetricians and Gynaecologists of Canada) state that artificial induction or augmentation should not be used for VBAC or "trial of labour" patients because of the risks of uterine rupture.
Another induction method is using Cytotec. Cytotec is thought to soften collagen. It's used to soften the cervix for inductions and is contra-indicated for women with previous cesarean scars due to it's possible effects on the previous uterine incision.
Copyright Mother Care 1999. Written by Connie Banack, CD.
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