Hormonal Changes in Labor
The hormonal control of labour is very complex and difficult to understand but it has certain similarities to driving a car. The mother's brain is the driver and her uterus is the engine. The baby is his mother's eyes in that his position inside her determines which way to turn the steering wheel. The three pedals control hormones. The clutch represents oestrogen, the foot brake represents adrenaline and the accelerator represents oxytocin. A car will come to a stop in three ways: by depressing the clutch and disengaging the engine, by stopping petrol supplies reaching the engine, and by using the foot brake. In pregnancy and labour, these functions are performed by stress hormones. As well as maintaining pregnancy, stress hormones control labour by regulating the power of the uterine engine.
The role of a birth attendant should be like that of a driving instructor rather than a back-seat driver. Education and encouragement are more helpful than grabbing the steering wheel and slamming on the dual control foot brake whenever the smallest mistake is made. A learner continually subjected to panic reactions by the instructor will lose self-confidence and may give up altogether. The better the driving instructor, the less likely learners are to crash and need the emergency services.
If the driver relies too much on the advice of a back-seat driver, particularly one who has never driven before but has learnt all he knows through watching other people drive cars, she is more likely to have an accident. If she lets the back-seat driver completely control her labour she is asking for trouble.
- Margaret Jowitt, Childbirth Unmasked, 1993
Physiologists know that in order for a woman to give birth, she needs to release a certain number of hormones such as oxytocin, endorphins, prolactin, ACTH, and catecholamines. The important point physiology can clarify is that all these hormones originate from the same gland--the brain. It is essential to stress that it is not the whole brain that is active as a gland, but only the old structures we share with all the mammals (hypothalamus, pituitary gland, etc.). We might say that when a woman is in labor, the most active part of her body is the primitive brain. Modern physiology could also explain that when there are "inhibitions" during the birth process (or for that matter, any sexual experience) such inhibitions originate in the new brain: the neocortical structures that support the intellect.
Physiologists also could explain a phenomenon that is well known by mothers who have the experience of unmanaged and unmedicated births. During the birth process there is a time when the mother behaves as though she is "on another planet," cutting herself off from our world and doing a sort of "inner trip." This change of conscious level can be interpreted as a reduction of neocortical activity. Birth attendants who have understood this essential aspect of the physiology of labor and delivery avoid any unnecessary neocortical stimulation that can interfere with the progress of labor....
Any situation associated with a release of hormones of the adrenaline family also tends to stimulate the neocortex and therefore to inhibit the birth process. This means that a laboring woman needs first to feel secure. This feeling of security is a prerequisite for the change of level of consciousness that characterizes the birth process.
- Michel Odent, "Knitting needles, cameras, and electronic fetal monitors", in Midwifery Today Issue. No. 37
If a man was told that he had to get an erection and ejaculate within a certain time or he'd be castrated, do you think it would be easy? To make it easier, perhaps he could have an IV put into his arm, be kept in one position, have straps placed around his penis, and be told not to move. He could be checked every few minutes; the sheet could be lifted to see if any "progress" had been made.
- Nancy Wainer Cohen & Lois J. Estner, Silent Knife, Bergin & Garvey, 1983
Plasma concentrations of B-endorphin rise significantly from 38 weeks to reach peak values during labour.... In in-vitro experiments, opioids have been found to inhibit the release of oxytocin by suppressing the electrical activity of hypothalamic neurons and by inhibiting electrically stimulated release from nerve terminals in the posterior pituitary. Studies on live animals have found that this inhibitory effect only operates during periods when oxytocin secretion is being stimulated.
Recent studies on rats have identified the dynamic interactions that emerge between oxytocin and opioids during late pregnancy and labour. In this species, plasma concentrations of relaxin progressively increase from mid-pregnancy and undergo a further surge prior to the onset of labour. Relaxin has been found to increase plasma concentrations of oxytocin just prior to the onset of labour by directly stimulating oxytocin neurons in the hypothalamus. During late pregnancy and labour, this action of relaxin has been shown to enhance opioid modulation of oxytocin. In both periods, the naloxone-stimulated increase in oxytocin is significantly greater in animals that have not been deprived of ovarian release of relaxin. This implies that the relaxin-induced release of oxytocin simultaneously enhances its opioid modulation.
The stimulatory effects of relaxin on the release of both oxytocin and opioids are thought to be exerted via an afferent pathway to the hypothalamus, rather than at the level of nerve terminals in the posterior pituitary....
During labour, rats have been found to release similar levels of oxytocin prior to naloxone stimulation, both in the presence and absence of relaxin. Despite this similarity, a smaller increase in oxytocin concentration results from naloxone stimulation, only in animals that have been deprived of relaxin. This finding suggests that in these circumstances, opioids are specifically modulating the relaxin-induced increase in oxytocin neurons in the hypothalamus. Further studies have indicated that this enhanced opioid modulation of relaxin-stimulated increase in oxytocin is preceded in late pregnancy by a desensitization in opioid regulation of oxytocin from the pituitary. During this period, naloxone has been shown to have a diminished inhibitory effect on the release of oxytocin from nerve terminals in the posterior pituitary gland. From these combined results, it has been suggested that activation of oxytocin neurons in pregnancy induces an opioid inhibition that largely operates to limit its secretion and stores to accumulate prior to the onset of labor. In late pregnancy, the enhanced activation of oxytocin and opioid neurons in response to relaxin may lead to a gradual down-regulation of opioid receptors in the pituitary.
This pattern of opioid regulation may play a part in initiating the storage of oxytocin during pregnancy and modulating its subsequent release in response to stimulatory and inhibitory influences in labour. During this process, oxytocin release is destimulated by the activation of sensory afferent nerve pathways and may also be inhibited by different forms of stress. Studies undertaken on rats have found that the rate of progress in labour is reduced in animals who are subjected to disturbance, compared to those left undisturbed.
- Mayes' Midwifery, 12th ed., Betty R. Sweet ed., Bailliere Tindall, 1997
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Midwifery Today's Online Forum
Two clients in the past two weeks gave birth in hospitals and were given IV antibiotics for Strep B in the birth canal. I have always been under the impression that Strep B in the birth canal carried a very small risk to the baby, and so it wasn't necessary to spend too much time stressing over it. It seems, however, that there is a trend, at least with the doctors in my area, to treat Strep B as an extremely risky thing - for example, one of my clients' baby was kept in the hospital for three days for observation because the mother had a labor under 5 hours, and the antibiotics hadn't had time to take effect. How risky is Strep B in your opinion? What have you done when you've encountered it with clients? Do you even test for it?
- Nedra, CBE, doula
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Question of the Week Responses
Q: I am a lay midwife and doula. I recently took
on a doula client with a rectal prolapse subsequent to her last delivery which
was a Pitocin induction, epidural, forceps to turn an asynclitic head followed
by vacuum extraction and shoulder dystocia. The McRoberts maneuver was used to
deliver the baby's shoulders. She was given an episiotomy. I'm not sure how deep
it went, but she doesn't believe it extended. I have searched for information
on rectal prolapse in my textbooks, but can find none. Does anyone know of remedies
(besides surgery), possible complications (she plans to labor at home,) or any
A: This pathology is seriously related to the degree of the prolapse, because the mucous of the rectum is exposed, so you should already have a previous diagnosis of the degree of prolapse. Maybe your client's pubococcygeal muscles were damaged as a consequence of the kind of traumatic delivery that she had before, and these branches of the levator ani muscles are the most dynamic part of the pelvis floor.
Of the cases which I have seen in 14 years as a midwife, three cases were very serious and all needed surgery. The worst I saw was in a woman who, after engagement of the fetus, had a necrosis of the rectum mucous tissue. After the birth she received medical treatment, but it was not enough and she needed surgery plus a transitory colostomy. Thus, you must consult the right specialist who can evaluate your client, maybe a surgeon proctologist or the obstetrician. Put her on an appropriate diet and give her exercises for the pelvic floor. I don't know if increasing the blood circulation with natural or medical remedies to avoid thrombosis will be anything but transitory.
Be sure about the size of the baby. Maybe he/she is too big and will cause you a lot of worry. I don't recommend birth at home.
- Sandra, midwife
A: I too have a rectocele from a shoulder dystocia and deep episiotomy from the birth of my son nine years ago. A year later I delivered another child without problems. But now, eight years later, I have had a very difficult pregnancy with constipation problems directly due to the rectocele. Use of suppositories has become routine. I'm wondering what this will mean to my labor/delivery also.
A: I am a Dutch independent midwife who does about a hundred births a year, of which about 90% at home. If I am worried about a special case, I have good contact with the gynaecologists in the nearby hospital, most of whom favour homebirths if they are medically possible. I think with some consideration homebirth might be possible for your client.
As a midwife I always get frustrated by hearing about an episiotomy "up to people's toes" as we call it, extended if shoulder dystocia occurs! Are there so many obstetric people who forget their anatomy lessons of the female pelvis?
As for the rectal prolapse, some physiotherapists in our country can treat it very satisfactorily after birth, so I think there must be some physiotherapists in your country as well who could treat that problem (I heard it is a painful and long treatment, but it helps).
I think your client's shoulder dystocia occurred also because of the terrible lie of the baby. It's a pity you didn't mention the weight of the baby and how many weeks your client was pregnant. If it was a large baby and she was "overdue," I'd suggest the following for this pregnancy:
- You cannot prevent a woman from having a large baby if there is no pathology (e.g., diabetes) so try to get her to deliver "on time." I suggest that in these cases my clients take 10 drops, three times a day, of the homeopathic Caulophyllum Talictroides in the D6 potention from 36 weeks on.
- Then I'd try to strip my client from 38 weeks on and when the contractions come, I'd give her a glass of water with 15 drops of Caulophyllum from which she has to drink one sip per half hour. I give this once, then the body has to do it by itself. Let your client have a bath as long as she likes to relax and reduce some of the pain. You can also suggest that she use a TENS unit. The Dutch website to rent such a thing is at http://www.geboortetens.nl I don't know a similar English site for these, but I know the geboortetens people are very helpful. When using the TENS (which comes with electrodes and easy instructions), several of my clients have felt an urge to push already when there is no full dilation, so beware! Let her puff like a dog during these contractions (about the time they reach 7 or 8 cm). If all goes well, there will be a point when the body takes over and she cannot avoid pushing. Let her push then, but only how her body says; don't let her push three times as you as a midwife are taught, but let her push the (mostly short) times your client's body "says" (this is the "reflectoir urge to push"). Maybe it would be a good idea for your client to have some yoga lessons so she learns to listen to her body.
When you let her go on like that by having her lying on the side of the back of the foetus the foetus gets more oxygen than when you force her into active pushing on her back. There will also be less pressure on the prolapse.
I'd not start the active pushing before the head is at the pelvic floor (Hodge 4) and I would have her pushing preferably on her side (beware--the baby comes out turning like a corkscrew,) or on all fours for minimal pressure on the prolapse.
If shoulder dystocia occurs you can at first try the McRoberts manoeuvre, but if you already have her on a side or on all fours, then have her stay on all fours and pull the fetal head firm to her sacrum. Don't be frightened, just do it. In most cases you'd get the "abdominal" shoulder out and with some manipulation the rear shoulder will follow. In one case I didn't get the baby out this way, also I didn't get the baby out by trying to get the rear shoulder first, so instinctively I got in with two fingers, which I laid at the shoulder blade of the sacral shoulder and I bent those a little and kind of rotated it under the symphysis.
The baby was born with an Apgar 7 after one minute and 10 after five minutes; I didn't have to use extra oxygen or my mucus extractor. Within half an hour after birth the baby nursed and he drank very well! There was also no sign of paralysis. I didn't have to break a clavicle, but this was a horrible experience, I can tell you. I don't think I could have done it without the help of the assisting nurse, so when you expect a big baby have a trusted assistant at the birth.
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From April 14 to 18, 2002 the 26th Triennial Congress of the International Confederation of Midwives will take place in Vienna, Austria. The call for abstracts and second announcement can be found at: www.icm-congress.com
Deadline for abstract submission: 30.5.2001
For questions: firstname.lastname@example.org
Order of copies of second announcement:
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- Dorothea Rueb
Org. Committee, ICM Congress 2002
I am a third-year student midwife training in England. As part of my training I am writing a report on midwifery in China. Does anyone have information on this subject or contacts with midwives working in China? I would be very pleased to receive information on this subject.
- Marie Ashford.
INTERNATIONAL MIDWIVES, please direct your questions, comments, and needs to "International Connections." We're here to help you!
I live in Lincoln in the UK. I am 19 years old and will begin my midwifery training on 24th September of this year. I wonder if you could give me advice or words of wisdom that would help me through my training and career as a midwife.
- Katie Mitchell
Editor's note: Here is a golden opportunity for midwives to give an aspiring midwife some support. Please take some time to answer her question from your heart.
Mindi asked in the 3/28/01 newsletter what was done about breech 100 years ago. When I first started studying birth in 1973, I ran across a book by a physician from, I think, the early 1900s. Unfortunately I can't remember the title or author. What I do remember is that his remedy for any obstructed labor was to do an internal version to breech and extract the baby by grasping its legs and drawing the baby down and through. Although there have always been a higher rate of complications with spontaneous breeches, it is interesting to me that converting to breech was seen as a way to rescue troubled births.
- Karen Ehrlich, CPM, LM
This is in response to the mother who asked about flax oil for fatty acid intake during pregnancy [Issue 3:16]: It is absolutely safe to take a teaspoon/capful of flax seed oil (pref. organic/high lignan) during pregnancy. I take flax seed oil every day and notice more regularity and energy, plus more.
In regard to the pending Oregon legislation [Issue 3:16]: Is this something specific to the Eugene, Oregon area? All Oregon zip codes were not listed. I would lend my opinion and support, but I need to know who to contact.
- Sharon M. Cooper
Editor's note: Will an Oregon person in the know please give E-News more information?
I am interested in research-based, clinical guidelines on "skin to skin" contact immediately following delivery regarding its effect on breastfeeding, maternal-infant bonding and thermoregulation.
University of Plymouth, Devon
Relpy to: firstname.lastname@example.org
ERRATUM: In E-News 3:16 the statement, Penny Simkin (1986) surveyed 159 new mothers and found that 765 of them said oxytocin drips were stressful and 46% said the same of amniotomy, should have read Penny Simkin (1986) surveyed 159 new mothers and found that 76% of them said oxytocin drips were stressful and 46% said the same of amniotomy. The editor regrets the error.
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