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Hormones of Labor

Easy Steps to a Safer Pregnancy - View e-book or Download PDF - FREE!
An interactive resource for moms on easy steps they can take to reduce exposure to chemical toxins during pregnancy.

Other excellent resources about avoiding toxins during pregnancy

These are easy to read and understand and are beautifully presented.

Subsections on this page:


This is a fabulous article from Mothering Magazine:

Ecstatic Birth: The Hormonal Blueprint of Labor
Issue 111, March/April 2002
By Sarah J. Buckley

Hormones in Labour (The Onset of Human Labour), by Sarah J. Buckley, MD at Women of Spirit

The Chemical Symphony of Birth by Patricia Blomme

Hormones of Labor - A very cool  infographic

WomenExplainedByOBs - a pictorial representation of the obstetric view that women have an ON/OFF switch controlled by pitocin.


Oxytocin and Vasopressin - My favorite hormones

Herbal Hormones

Pharmacology of parturition.
Roy AC, Arulkumaran S
Ann Acad Med Singapore 1991 Jan;20(1):71-7


Ann N Y Acad Sci. 2004 Dec;1032:224-7.
The neurobiology of trust.
 Zak PJ, Kurzban R, Matzner WT.

This is the first report that endogenous oxytocin in humans is related to social behaviors . . . We conclude that oxytocin may be part of the human physiology that motivates cooperation.

Anti-Cheating Hormone [November 27, 2012] - The hormone oxytocin has many functions in the human body. Scientists now think it may also help deter cheating. 

10 Reasons Why Oxytocin Is The Most Amazing Molecule In The World [7/12/12]

Hug The Monkey - how oxytocin, the hormone of love, lets us trust and mate.

The perinatal application of oxytocin and its potential influence on the human psyche from Hug The Monkey
Christof Plothe, D.O., BSc., (OST), H.O.N.S., M.R.O., DPO, HP
Paper to be published in the ISPPM Journal, Spring 2010

Love Chemistry: The Book by Elaine Fisher

The Association for Psychological Science has some great articles about oxytocin!

Trust in oxytocin -  . . . The hormone oxytocin (applied as a nasal spray in this experiment) increases an individual's willingness to trust someone.

Some articles in the popular press about this study:

Building trust via nasal spray By COLIN FREEZE [6/2/05]

Tests reveal 'trust in a bottle' hormone, from CNN

‘Cuddle hormone’ - Research links oxytocin and socio-sexual behaviors from oxytocin.org

Mom-Made Hormone Shields Baby During Birth [12/15/06]
Oxytocin tells fetal brain to conserve oxugen, study finds

Science 15 December 2006:
Birth entails a multitude of transitions. Studying rats, Tyzio et al. (p. 1788) have identified yet one more, a link between oxytocin exposure and the switch in how certain brain neurons fire. The neuro-transmitter GABA (-aminobutyric acid) is usually excitatory in fetal brain neurons but inhibitory once they mature. Exposure to oxytocin during parturition causes a switch from excitation to inhibition in GABA signaling. This quieting of neuronal activity may serve to protect the brain against transient hypoxia during birth.

Maternal oxytocin triggers a transient inhibitory switch in GABA signaling in the fetal brain during delivery.
Tyzio R, Cossart R, Khalilov I, Minlebaev M, Hubner CA, Represa A, Ben-Ari Y, Khazipov R.
Science. 2006 Dec 15;314(5806):1788-92.

We report a signaling mechanism in rats between mother and fetus aimed at preparing fetal neurons for delivery. In immature neurons, gamma-aminobutyric acid (GABA) is the primary excitatory neurotransmitter. We found that, shortly before delivery, there is a transient reduction in the intracellular chloride concentration and an excitatory-to-inhibitory switch of GABA actions. These events were triggered by oxytocin, an essential maternal hormone for labor. In vivo administration of an oxytocin receptor antagonist before delivery prevented the switch of GABA actions in fetal neurons and aggravated the severity of anoxic episodes. Thus, maternal oxytocin inhibits fetal neurons and increases their resistance to insults during delivery.

In utero production of oxytocin

The demonstration that the rat uterus is a major site of oxytocin gene expression during the late stages of pregnancy resolves the apparent paradox between the powerful actions of exogenously administered oxytocin and the lack of unequivocal evidence for a role of  circulating
oxytocin. These findings suggest that, with respect to parturition, oxytocin may act locally rather than as a circulating hormone.

Oxytocin and Emotions

The lay press book with the best explanation I've seen so far on the role of oxytocin in human emotion is called A Natural History of Love by Diane Ackerman and is found (in my bookstore) in the sociology/anthropology section. The part specifically dealing with oxytocin is on pp. 162-164. It is not well footnoted, so I can't give you the journal articles she used, but there is a lengthy and excellent bibliography.

The classic work describing early research into the emotional aspects of oxytocin, especially as it relates to breastfeeding is Maternal Emotions by Niles Newton. This was first published in 1955, but has been reprinted many times. Dr. Newton was a trailblazer in the field of the physiology of female sexuality in all its aspects, including lactation. Her excellent chart showing the parallels between uninhibited, undrugged childbirth and sexual excitement is an eye-opener and remains quite revolutionary to this day. Many of the responses she describes can be related to the effects of oxytocin.

Plasma Oxytocin Levels May Mediate Emotional Experiences

Preliminary research on plasma oxytocin in normal cycling women: investigating emotion and interpersonal distress.
Turner RA, Altemus M, Enos T, Cooper B, McGuinness T
Psychiatry 1999 Summer;62(2):97-113

Orgasmic Birth

People often ask  me if orgasmic birth is really a possibility.  Yes, definitely!

Let's be clear about what we're talking about: Birth can be orgasmic in the same way that chocolate can be orgasmic . . . a transcendental experience that one always remember with great satisfaction.  This is the most that you can really hope for if you're giving birth attended by strangers or in any situation where you feel self conscious.

However, I have been privileged to be present at a couple of homebirths where the women truly seemed to have orgasms as the baby emerged.  One of them said, "That was fabulous!" as she proudly held her baby in her arms.  The other said something like, "Oh, I could do that again right away!"  In both cases they seemed to experience the "fetal ejection reflex" that Michel Odent writes about.  One was on hands and knees on her bedroom floor, leaning into her husband; she was very comfortable with her sexuality, and nothing I did was inhibiting to her.  The other was using a TENS machine to generate endorphins before she got in the birth tub for the last 5 minutes; her husband had run out for an urgent errand when her labor seemed not to be progressing 15 minutes earlier, so she was essentially alone in the tub.

Orgasmic Birth - the movie!

The Functions of the Orgasms: The Highways to Transcendence by Michel Odent

Check out this summary of CHAPTER TWO


-         Emergence of new perspectives
-         The fetus ejection reflex
-         Climbing towards the ultimate steps
-         A crucial moment
-         A powerful hormonal flow
-         The real climax

Adrenaline Can Stop Labor

From newsweek, July 23, 2001 re: "Chokehold"

Serving at Match Point in the Wimbledon final last week, Goran Ivanisevic felt the weight of imaginary sandbags on his arms.  Why should nerves paralyze an athlete about to win?  Being tantalizingly close to an unexpected victory can cause what sports psychologists call overarousal.  The body produces excess adrenaline while restricting blood flow, tightening the muscles and depleting fine-motor skills.  Oddly enough, Ivanisevic didn't have trouble lifting the Wimbledon trophy.

I wish I understood your statement a little better, but it's sort of "Greek" to me. I do know that an adrenaline rush can stop a labor, I guess it has to do with the relationship of hormones in the body. ???

Hope you don't mind, but I think we should put this out on the list. I think it is important, not only to getting pregnant, but also to growing healthy babies.

There is a fairly large body of research, though it seems that not many in the AMA want to pay much attention to it, that shows that adrenaline and other catecholamines (fight or flight hormones) have a vasoconstrictive effect on the female reproductive vessels, and thus perfusion. In fact adrenaline (epinephrine) is one of the few that can counter the vasodilating effects of the hormones of fertility (estrogen). This is thought to be a major cause of miscarriages during stress (death of a loved one, natural disasters, etc.), irregular periods in some women leaving home for the first time to enter college, and other situations.

I have often wondered about the stress associated with fertility clinics and the high failure rates and this relationship. I know of no fertility clinics that use TM or other stress reducing techniques. For families going through the process, it is quite stressful, not only for the constant anxiety of "are we pregnant yet?", but it can be like having the Gynecologist & Nurse in bed with the couple, not to count the $$$ stress.

For more information check out:
Resnik R: Anatomic alterations in the reproductive tract, in Creasy RK, Resnik R, editors; Maternal-Fetal Medicine: Prin. & Practice, 2nd ed. W. B. Saunders, 1989, p. 137-140.
Resnik R; The endocrine regulation of uterine blood flow in the nonpregnant uterus: A review; Am J Obstet Gynecol, 1981; 140:151-156. or, of course:
DuBose TJ; FETAL SONOGRAPHY; W. B. Saunders Co. 1996, p. 345-351.

All of these will give you references to many more articles on the topic.

Circulating adrenaline (from the adrenal cortex) appears to cause vasoconstriction in the uterus (and hence increases pain because of hypoxia). In the brain a whole range of neurotransmitter chemicals that are involved in stress responses appear to inhibit the secretion of oxytocin...........and thus also have an effect on the uterus. I have quite a lot of references for this - physiology papers, reviews etc. - and Michel Odent has also been writing about it generally for a while.

The level of anxiety appears to determine the amount of adrenal involvement in any stress response. The work of Frankenhauser in the seventies - quoted all over the place in Health Psychology texts - is really applicable to labour, cessation of periods in anorexics and athletes etc., and there are lots of models being used just now for all kinds of generalised stress responses.

Why does the presence of a doula decrease the pit rate?

When a woman feels safe (as she usually does with a doula) then she releases oxytocin, which stimulates labor and therefore does not need pitocin (synthetic oxytocin) to help her labor. If a woman does not feel safe, she releases adrenaline, and adrenaline tends to stop labor.

This (release of adrenaline when under stress) is part of the "fight or flight" mechanics of our wonderful endocrine systems.

In the animal kingdom, if one is threatened, fright causes the release of adrenaline, which stops labor, enabling the animal in the throes of birth to stop birthing, and run away to safety.

Sometimes we need to be reminded that we are indeed animals, and that these primal mechanics are still at work within us.

Have you seen the video about breast self-attachment in newborns? This video (I can't remember the exact title, sorry) demonstrated a study regarding self-attachment in newborns, in various groups (i.e., medicated vs. unmedicated). The babies in the unmedicated group, when placed on the mother's abdomen, lifted their little heads, and crawled up to the breast under their own steam, with no help from the mother - just like we've all probably seen puppies or kittens do.

Just another example that our bodies (with rare exceptions) are quite capable of birthing and nurturing babies without intervention, as long as we feel safe and protected. Just like our animal friends.


Researchers find more receptors and more roles for relaxin

Endorphins and other Pain-Relieving Hormones

See also: Birth Trauma - Drugs Used in Labor Suppress Bonding Instincts

and Birth Trauma - Unmedicated Births More Comfortable for Baby

The Endorphin Connection - This site is really about the use of ACU-TENS to treat addictions, but it starts with some interesting explanations of "The Nature of Pain", and "Pain and the Nervous System".

How Endorphins of Natural Childbirth Can Heal Birth Trauma for Older Siblings

Study: Placebos, Drugs Both Activate Brain in Pain Relief

Both placebos and strong painkillers activate the same areas of the brain, which suggests that pain relief may often be literally a case of mind over matter, researchers said on Thursday.
. . .
The experiment also suggests the brain has a built-in mechanism for dealing with pain, which might someday lead to the development of better drugs to treat pain, the researchers report in Friday's issue of the journal Science.
. . .
''Placebo treatment and treatment with painkiller of the opioid family, they induced activity in the same region,'' Ingvar said in a telephone interview.
. . .
What was unexpected was that the people who responded most strongly to the drug also responded most strongly to the placebo injection, Ingvar said. Perhaps they have stronger pathways in the brain for pain relief, he guessed.
. . .
Pain is a valuable mechanism to warn that something is wrong, but once a person is aware of an injury, disease or damage and is taking care of it, pain loses its value.
. . .
''Pain, once you know it hurts, it's just pain,'' he said. [Reuters, 2/7/02]

Endorphins!!! Tell me about it. I was ready to do the whole thing over again after I gave birth. I was blessed to have only a 5 hour labor with him and he is my first. I've heard that each labor after gets shorter than the one before, so I guess i better watch it. =) Only three weeks after he was born, I asked my dh, "When can we have another one?" =) I was on such a high! =)

In my studies of the hormones of birth, I've learned that the stress of labor causes a woman's body to release endorphines to ease the pain and to facilitate a primal bonding with her baby. In a natural labor, the levels of these hormones are significant, and they are passed through to the baby also to ease the stress on the baby.  As a fun side effect, the endorphines seem to fill the air around the laboring woman so that her birth attendants also get to enjoy them.  There's a reason why birth attendants sometimes call themselves "natural birth junkies".  :-)

Endorphines are the "love hormones" released during sex, childbirth and breastfeeding, and they really are like an aphrodisiac, causing people "under the influence" to fall in love with each other without any rational filtering.  I try not to usurp the power of these hormones, and I work hard to keep the family focused on each other in that first hour after birth, because I want them bonding with each other instead of with me.

Well, these endorphines can have a wonderful healing effect for couples who have had a past traumatic birth, as the mom is under the influence of nature's finest "narcotic", and the dad absorbs them from the air around her.  But it was this message that really helped me to understand that this also pertains to the older children who were born through a traumatic birth process.

Well, dhuh.  It just never occurred to me before.

So, chalk up one more benefit of natural childbirth - it can be used to help little ones heal from their own birth trauma and enjoy a level of bonding with their parents that they missed out on at their own births. 

I really like this theory.  It is great that it offers hope to families who have had a traumatic past birth experience, and it sort of explains why my desire to give birth again, or even to watch someone else giving birth, is reaching addiction proportions.  In fact the whole pregnancy and birth experience for me was just one big trip. It also partly explains why I fell in love with my two midwives (even if I never see them again, I shall still regard them as some of my dearest friends).  I think it also could explain why fathers bond so well with the babies after a tranquil homebirth, compared with an aggressive hospital delivery - one of my most precious memories is of my husband holding our baby boy in his arms while I was lying on our sofa having my tear stitched.  He was sitting in the doorway on a kitchen chair and he happened to look up from James and smiled at me as I glanced towards him .. you could almost feel the love in the air.

How do you think the endorphins get into the air?  Perhaps from the mothers breath or sweat, do you think?  Or maybe the excitement and happy emotions of the event stimulate the sympathetic production of similar chemicals in the bodies of the people around?  I suppose many forms of excitement are contagious in a confined situation, and birth *is* a particularly focussed and centred event.  If you accept the theory that the happy hormones are given off by by the mother, it presumably works the other way around in unhappy situations where fear and unhappiness are transmitted between people and to the mother.

I suppose the transfer of the endorphines could be from the sweat of the mother, just like when you have several women living together they start ovulating at the same time after a while. 

I wonder if that is why I had four midwives at my birth.  One midwife didn't want to leave when she should have at 5pm, she ended up staying until 10pm.  Once I had birthed, I just wanted to do it again and the feeling didn't leave me for ages, I still feel envious when I hear birth stories or see pregnant women.  I was in a state of euphoria for ages until I saw the worried faces re. my "retained" placenta.

Are these endorphins somehow masked in medicated births?  I just never felt that same "love" for the OB who made jokes, scalpel in hand, while he performed my episiotomy during my first birth. : )

Yes, see Birth Trauma - Drugs Used in Labor Suppress Bonding Instincts

Only slightly related, but:

Recent research shows that chili peppers contain a chemical, capsaicin, which has been shown in lab rats to dull the pain-killing effects of the G spot; it's not clear how long this effect lasts, but the little I've been able to find indicates that it's probably a relatively long-lasting effect and possibly cumulative.

Beyond the g spot: New research on human female sexual anatomy and physiology*, Whipple B,  Scandinavian Journal of Sexology, Volume 3 no. 2

The ``G'' Spot May Govern Pleasure And Pain  By Amy Norton
 NEW YORK (Reuters Health) - A woman's erogenous zone may exist for more than mere pleasure. Researchers say evolution may have designed the so-called ``G'' spot to ease the pain of childbirth.

[In case you're wondering how you can learn more about capsaicin, you can start at Mike's Pepper Garden - Pepper Science.  And if you're wondering which peppers have the most capsaicin in them, you'll want to investigate the Heatscale.

Midwife/Doula Pheromones Reduce Labor Pain

Biobehavioral responses to stress in females: tend-and-befriend, not fight-or-flight.
Taylor SE, Klein LC, Lewis BP, Gruenewald TL, Gurung RA, Updegraff JA.
Psychol Rev. 2000 Jul;107(3):411-29. Review.

Scientific evidence that a woman in a stressful situation will do better with another woman around. [University summary]

I came across this information in Pre- and Perinatal Psychology Journal, Fall, 1996.

In reference to non-pharmaceutical pain relief for laboring women:

"Supporting physiological evidence includes findings that endorphin levels are influenced by the hypothalamus, which is affected by 'pheromones
given out by birth attendants . . . the chemistry of confidence of traditional midwives is . . . very different from the chemistry of fear and doubt . . . in
the atmosphere of a modern hospital.'"

Maybe we shouldn't be taking so many showers or using deodorants? :-)

This is so cool!!! I'm not sure that pheromones are much effected by showering and deodorant, seems like I've read that they are at a much higher
level of receptiveness.....kind of like ultrasound, only ultrasmell!!!!!

Father's Hormones

The Making of a Modern Dad - fathers undergo hormonal changes that prime them for parenting.

Hormonal correlates of paternal responsiveness in new and expectant fathers.
Storey AE, Walsh CJ, Quinton RL, Wynne-Edwards KE.
Evol Hum Behav. 2000 Mar 1;21(2):79-95.

Little is known about the physiological and behavioral changes that expectant fathers undergo prior to the birth of their babies. We measured hormone concentrations and responses to infant stimuli in expectant and new fathers living with their partners to determine whether men can experience changes that parallel the dramatic shifts seen in pregnant women. We obtained two blood samples from couples at one of four times before or after the birth of their babies. After the first sample, the couples were exposed to auditory, visual, and olfactory cues from newborn infants (test of situational reactivity). Men and women had similar stage-specific differences in hormone levels, including higher concentrations of prolactin and cortisol in the period just before the births and lower postnatal concentrations of sex steroids (testosterone or estradiol). Men with more pregnancy (couvade) symptoms and men who were most affected by the infant reactivity test had higher prolactin levels and greater post-test reduction in testosterone. Hormone concentrations were correlated between partners. This pattern of hormonal change in men and other paternal mammals, and its absence in nonpaternal species, suggests that hormones may play a role in priming males to provide care for young.

When new dads go gooey-eyed, blame their hormones - from the web pages of the New Scientist

From the London Times:

'Men are biologically programmed to be soppy after their children are born. A study shows that hormone changes put fathers through similar emotional rollercoaster to that experienced by Mothers.

Levels of testosterone, the male sex hormone, crash by an average of a third just after a baby is born. The lower it goes, the more a father dotes on the newborn. The effects, reported in New Scientist, are thought to be an evolutionary device to create an emotional bond with mother and child and make men less likely to stray.

Studies show that most male birds, rats and some primates are primed for their young in this way, but Anne Storey, a researcher at Memorial Hospital, in St John's, Newfoundland, found the effect in humans. Dr Storey who analysed blood samples from 34 couples, found that hormone changes in fathers were triggered even by watching videos of newborn babies.'

(Helen Rumbelow - The Times)

Personally I also found that the pregnancy affected my DH as well.  He had the heartburn, piles, backache that didn't really affect me - poor little sausage!!!  :-)

After our first child was in dh came into recovery sobbing!  I thought something was wrong w/our son.  He was pretty emotional after each baby. IT's great to fall in love all over again w/your spouse.  I'll never forget seeing him in such a different light after our first was born.. Thanks for reminding me of that!

My hubby cried when our boys were born and every once in a while, he'll get tears in his eyes while watching them.  He also wept when we lost our babies.  In fact I remember when we lost our first baby he sat outside and held that baby, no bigger than my small thumb and just wept for that child.  Then we buried her, (i think) in our yard.  all of our babies are buried there.  It was a bittersweet moment to bury our placenta from our newborn out there as well. Thanks for your kind posts about our losses.  It was very difficult and makes us more thankful for our children.  It's still a hard question to answer "how many children do you have?"  I consider my angels as part of our family, even though we didn't really get to meet them and they are not here.  Most people don't acknowledge their existence and think I'm nuts for not forgetting them.  Oh well.  I can't forget them :

I wonder if this is why people used to want to have children in order to save their marriage.  I would also love to know what triggers this hormonal change in the father.  Is it the endorphins produced by the mother?  I notice that this study comes out of England, where they have a significantly lower use of epidurals than here in the U.S.  Does the hormonal change in the father occur only with natural childbirth?


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