Why the Vagus Nerve is so important during pregnancy

By Carolyn Tallents

A simple guide for using your breathing to strengthen your body in less than 5 minutes per day – pregnant or not!

Triggering the reflexes governed by your Vagus Nerve (VN) can dramatically affect your well-being, the health of your unborn child, and potentially the trajectory of your labor and delivery.  In this article, we’ll give you a brief overview of how the VN affects human beings in general, and use this as a launchpad for you to understand how to use this information for your pregnancy, postpartum period, and fertility. 

Since “your left and right vagal nerves contain 75% of your parasympathetic nervous system’s nerve fibers,” this incredibly important branch system of nerves is considered to be “the main nerves of your parasympathetic nervous system.”  The parasympathetic nervous system (PNS) is the portion of human physiology that controls the body’s ability to relax, often called “rest and digest” or “feed and breed;” this system is most responsible for directing the internal chemical activities of reproduction, digestion, immunity, mood and more.

The VN is actually a pair of nerves, which together are classified as #10 of 12 cranial nerves.  It originates in the brain stem, runs down each side of the neck, and “follows a complex course throughout the body to innervate several organs” as well as muscles. It passes through the diaphragm’s crural opening alongside the esophagus, and reaches into the ovaries and cervix.

What is Appropriate Vagus Nerve (VN) Activation?

Stimulating the VN is something that modern medicine is attempting to command, even though every person on the planet can attain it autonomously. 

PRACTICE #1:  Get started right now by shifting your inhale through your nose, and a bit slower and lower into your abdomen, as you read on.

 

“Vagal tone is an internal biological process that represents the activity of the vagus nerve.” “Really strong vagus nerves [are considered to arise from] high levels of activation in that bundle of nerves” via nerve “impulses”.  So,even though the medical treatment known as vagus nerve stimulation (VNS) uses electrical impulses/signals from a device implanted just beneath chest skin near the left vagus nerve, human beings are capable of sending our own electrical impulses by just breathing differently (more on this later)!

Conversely, the VN can also over-react (called “vagal response” or “vasovagal syncope”), causing symptoms as dramatic as fainting. In other words, the precise and appropriate function of this vital nerve is critically important, which is why holistic treatments like “getting good sleep” and “staying well hydrated” are also sometimes suggested treatments for the VN. 

How the Vagus Nerve (VN) Affects People

The FDA has actually approved VNS for epilepsy and depression, and activating this nerve is being investigated for the treatment of headaches, inflammatory bowel disease (IBD), post traumatic stress disorder (PTSD), arthritis, and pain. There is now also evidence for VN activity to affect gut bacteria (microbiome), with “beneficial effect[s] on mood and anxiety.” Considering that the VN is considered to be “the” parasympathetic de-stressing nerve, it’s no wonder the researchers are scrambling to study these effects and more.

To be clear, stimulating this nerve wakes it up to do its job, which is to turn on the PNS, which improves multiple known health measurements, including increasing heart rate variability (HRV), lowering heart rate and blood pressure, better immune function, inhibiting the “fight or flight” of the acute stress response, increasing relaxation, and even activating anti-inflammatory pathways. 

But it gets even better.

According to Dacher Keltner, Ph.D., founding director of the Greater Good Science Center and  professor of psychology at the University of California, Berkeley, some studies suggest the VN is interconnected with networks of the love hormone, oxytocin. Keltner calls it the “caretaking nerve,” helping us to communicate and empathize, passionately describing his own scientific research studies with the following details:

  • “Images of suffering activate the vagus nerve…If somebody tells you an experience of, say their grandparent dying, your vagus nerve fires.  If they tell you an inspiring story, their vagus nerve fires.  It’s getting ready for feelings of compassion…The more I feel compassion, the stronger the vagus nerve response…In that state of having a strong vagus nerve response, I feel common humanity with many different groups. I’m feeling connected to people with different political persuasions, different ethnic origins…deep ethical intuitions…”
  • Conversely, however, “The more I feel pride, the weaker the vagus nerve response.”

Keltner describes what a “strong vagal profile” would look like in a human being: “more positive emotion on a daily basis, stronger relationships with peers, better social support networks,” these are the people more likely to intervene with bullies or spend recess helping a friend with homework. 

Strong vagal tone, in other words, represents the kind of person many of us aspire to be. 

How the Vagus Nerve (VN) Affects Pregnancy & Postpartum

Pregnancy needs both the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS) to work in harmony in order to optimize pregnancy wellness and fetal health.,,, At the very least, the VN contributes to the autonomic nervous system (ANS), including its key governance of the PNS, which is a primary influencer over stress-response, and therefore over a healthy pregnancy for both mom and baby. Therefore, a healthy vital pregnancy and postpartum needs the VN to function optimally. 

The reality is that most reproductive studies thus far have been done on VNS (the electrical box implant in the chest), rather than the free treatment of breathing.  And, well, the studies are all conclusive that vagal nerve stimulation is critically helpful:

  • “VNS therapy provided effective treatment for [treatment-resistant depression] during pregnancy and delivery. VNS was safe for the patient and her child.”
  • “Our findings indicate that maternal VNS treatment is safe during pregnancy and has a protective effect in a pregnant rat model of preeclampsia.”
  • “At-home, noninvasive auricular vagus nerve stimulation (aVNS) therapy is well-tolerated and associated with a significant reduction in postpartum depressive and anxiety symptoms.”

Moreover, a 2021 Frontiers in Neuroscience study clearly states how the VN is so critical at every stage of reproductive development for the fetus: “Autonomic nervous system regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus’ development. In particular, several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal, and postnatal life: from the regulation of inflammation…which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body.” 

All of this points to the critical necessity of proper development of the fetus’ VN.

This 2021 Frontiers in Neuroscience study then discussed the scientific evidence that the infant’s VN has better control of cardiac function when birth occurs as “spontaneous labor without analgesia” as compared to C-section deliveries.  In fact, a newborn’s own well-developed ANS has been found to respond more “efficiently to umbilical cord clamping,” saving the little one from the problems associated with low oxygen.  

Various factors of fetal growth are known to mirror that of the pregnant mother, from patterns of stress and inflammation response, to cell signaling, to sleep-wake patterns, use of drugs for pain relief, all of which are various symptoms as well as causes of sub-optimal vagal nerve development. And since “social/emotional development is related to the vagal system, any insult such as maternal distress…will interfere with the maturation of the [outermost layer of the fetal brain and disruption of] the Social Engagement System of the child…Moreover, an impairment in vagal balance, particularly a decreased tone, might be implicated in depression, anxiety, post-traumatic stress disorder, and schizophrenia.”  

Finally, the vagus nerve innervates the cervix and ovaries, with rat studies showing that loss of vagus innervation in the mother may delay the birth process itself. 

PRACTICE #2:   Take one soft inhale and purposefully elongate/extend your exhale longer than the length of your inhale, right now. 

 

How the Vagus Nerve (VN) Affects Fertility/Infertility

A 2021 research request showed interest in studying the vagus nerve for male fertility, hypothesizing that the “VNS might help in treating male infertility caused by inflammation.”  The methodologies hypothesized included the role that vagal nerve stimulation may have on sperm creation and transport, ability for sperm to penetrate the egg (capacitation), sperm motility, sexual motivation, facilitated ejaculation, sperm count and more.

In women, since “natural selection has linked the physiological controls of energy balance and fertility such that reproduction is deferred during lean times, particularly in female mammals,” the data the VN picks up from the stomach may help modify or control reproduction.

Polycystic ovary syndrome (PCOS) is one of the most common causes of infertility in women. A 2013 study in Reproductive Biology and Endocrinology specifically looked into the relationship between the VN and PCOS in rats, wrote, “the vagus nerve serves as a communication channel between the ovaries,” and summarized its findings, “these results suggest that the information arriving to the ovaries through the vagus nerve participates in regulating ovarian functions…” 

For both men and women, just being able to have sex in the first place is increasingly hindered and related to lack of ANS and VN function: “sexual responses are mediated by the coordinated activity of sympathetic, parasympathetic, and somatic innervation” affects erections and secretions, as well as the muscle contractions of orgasm, ejaculation and pelvis.

How’s that for a wake-up call to get the VN up and running right now, guys and gals?! 

How to Work with Your Vagus Nerve (VN)

Fit For Birth’s Pre & Postnatal Corrective Exercise Specialist Certification introduces a topic called “the flatliners” referring to a population of people who are apparently so tired that they need coffee/caffeine to get going in the morning, and yet are unable to fall asleep quickly or deeply at night – despite their obvious fatigue, even increasingly reaching for sleep medications. In his landmark book called Breath, James Nestor says that these half-asleep and half-awake states of half-anxiety can only half-support the organs, causing “communication between the organs and the brain [to] become choppy, like a conversation through a staticky phone line.” 

The VN, after all, is one of the most important communication channels in your body.  

Commenting on the “implanted electrical nodes” that modern medicine uses as an “artificial vagal nerve” to restart blood flow and communication, he suggests “another, less invasive way…to stimulate the vagus nerve: breathing.”  Tons of research put into his 2020 book leads Nestor to give the following advice on how to get your vagus nerve in harmony for both ends of the ANS spectrum: “Willing ourselves to breathe slowly will open up communication along the vagal network and relax us into a parasympathetic state. [On the other end of the spectrum,] breathing really fast and heavy on purpose flips the vagal response the other way, shoving us into a stressed state. It teaches us to consciously access the autonomic nervous system and control it, to turn on heavy stress specifically so that we can turn it off and spend the rest of our days and nights relaxing and restoring, feeding and breeding.”

Two Exercises to Condition Your Vagus Nerve (VN) Response

  1. Breathe Slower & Longer to stimulate your VN to activate your parasympathetic nervous system (PNS).  There are dozens of ways to do this, so feel free to create something that works for you.  Here is one method:  Inhale for a count of about 5.5 seconds and exhale for a count of about 5.5 seconds.  Various historical traditions have used 5.5 liters per minute to be “optimal breathing,” which equates to 5.5 breaths per minute, incredibly also equating to 5.5-second inhales and exhales. Recent scientific research has validated that 5.5-second breathing achieves greater heart rate variability (HRV), a well-known measure of overall health and vitality. You can practice this with every one of the 20,000 breaths that most people breathe each day, and multiple health measures would improve. However, purposefully sitting to practice for a few minutes per day as your meditation is a wonderfully achievable and health-filled practice that can soon start to carry over into daily life activities. 
  2. Breathe Faster & Deeply to train the contrasting VN response, activating your sympathetic nervous system (SNS).  Both the Tummo Inner Fire Breath and Wim Hof techniques exemplify this breath pattern, consisting of strong and fast inhales through the nose into the ribs and abdomen, followed by strong and fast exhales, often through the mouth.  Becoming lightheaded is normal & expected during this type of breathing, including the possibility of passing out as well as eliciting mystical experiences. Therefore, please do not consider this information medical advice, and consult a medical professional who is knowledgeable about breathing techniques, especially if you’re pregnant.  Fast Breathing would more commonly be performed at certain times: waking up in the morning instead of coffee, at any time that you want to produce more energy for your day, preparing for an athletic event, any time you’d like to elicit a “fight or flight” response, or as part of a meditation experience. 

Which Breathing Is Right for Me?

As a human being, regardless of whether you are pregnant, postpartum, undergoing fertility treatments, or having nothing to do with the birthing world, you need both SNS and PNS to work optimally, on both sides of your ANS. Most modern humans are massively underperforming their natural rhythmic cycles, and therefore need to practice both of these techniques. At the same time,  remaining open to sensing which technique may be more often beneficial for your specific body type is how you’ll “know yourself” – the underlying tenet of meditation or ancient yoga.  Some of you may find that Slower & Longer feels more balancing/helpful for you, while others may find that Faster breathing feels more balancing/helpful.  Even more, what you find to be true today will likely change in the weeks, months, and years to come, depending on stress levels and life cycles. So be open to actually feeling your body; this is super important. No one will ever learn your body, and be able to advise you better than you. 

If all else is equal and you’re not sure where to start, you can follow this suggestion:

  1. Plan into your calendar a daily time to sit peacefully and practice conscious breathing for about 10 minutes. Schedule this into your calendar right now. During this time, practice one breathing exercise on each end of the spectrum, so you can build your familiarity:
  2. Perform FAST & DEEP Breathing for about 30-60 seconds, or perhaps 20-40 breaths. Pause for the next minute or so to feel your body. Don’t be in a hurry, just observe your breathing rate as it falls back to more natural, and feel for the humming in your energy field. Spend a minute or two here, in feeling meditation. Imagine how this is training your internal chemistry to be able to perform strongly in challenges like sports performance, rising above negative emotions, or the “marathon” of labor & delivery. (If you are pregnant, consult a medical professional who is knowledgeable about breathing techniques.)
  3. Perform SLOW & LONG Breathing for about 2 minutes, or perhaps 10 breaths. You can use a timer to gauge the 5.5 seconds (or count to 6 in and 6 out, which gives you 5 full breath cycles per minute). Again, close your eyes, pausing to feel your body as you now observe (rather than control) your breathing. Imagine how this is training your internal chemistry to be able to relax quickly and deeply, even letting your mind drop into the brainwaves of sleep if you’re able. 
  4. That’s it! Reward yourself for developing a new healthful habit! One round of each is amazing and probably will take less than 10 minutes.  You can always do a second round if you feel the enthusiasm for it. Once per day for the next three weeks, with the mindset of crafting your sympathetic and parasympathetic response is an incredible practice that will quickly start to seep into the rest of your day.  Research into forming habits suggests that you may want to consider rewarding yourself for each completion, perhaps putting a few dollars into a jar that you can spend after you’ve completed 3 weeks of practice. If you notice that one method seems better for you right now, then focus more on that end of the spectrum for the next few weeks!  Have fun, as you get to know your body.

To learn more about how to have your healthiest pregnancy possible, train with us! You can check out our one-of-a-kind personal training program here!

 

REFERENCES

(n.d.) Vagus Nerve. Physiopedia. Retrieved 9/13/22 from https://www.physio-pedia.com/Vagus_Nerve

  1. Baquiran, Maximo. Bordoni, Bruno. Anatomy, Head and Neck, Anterior Vagus Nerve. StatPearls [Internet] NIH. Retrieved 9/13/22 from https://www.ncbi.nlm.nih.gov/books/NBK547696/
  1. Baquiran, Maximo. Bordoni, Bruno. Anatomy, Head and Neck, Anterior Vagus Nerve. StatPearls [Internet] NIH. Retrieved 9/13/22 from https://www.ncbi.nlm.nih.gov/books/NBK547696/
  1. Linares, et al. Unilateral or bilateral vagotomy induces ovulation in both ovaries of rats with polycystic ovarian syndrome. Reproductive Biology and Endocrinology. Retrieved 9/13/22 from https://rbej.biomedcentral.com/articles/10.1186/1477-7827-11-68
  1. Clyde, et al. Transection of the Pelvic or Vagus Nerve Forestalls Ripening of the Cervix and Delays Birth in Rats. Biology of Reproduction. Retrieved 9/13/22 from https://academic.oup.com/biolreprod/article/84/3/587/2530350

 2020, Aug. 25. Diaphragm: Surfaces, Relations, Opening, Development. Notesmed. Retrieved 9/13/22 from https://notesmed.com/diaphragm-development-html/

  1. Fallis, Jordan. How to Stimulate Your Vagus Nerve for Better Mental Health. Retrieved 9/13/22 from https://sass.uottawa.ca/sites/sass.uottawa.ca/files/how_to_stimulate_your_vagus_nerve_for_better_mental_health_1.pdf
  1. YouTube: Greater Good Science Center. Dacher Keltner on the Vagus Nerve. Retrieved 9/13/22 from https://www.youtube.com/watch?v=5d6e_Un6dv8
  1. Breit et al. Vagus Nerve as Modulator of the Brain–Gut Axis in Psychiatric and Inflammatory Disorders.  Frontiers in Psychiatry. Retrieved 9/13/22 from https://www.frontiersin.org/articles/10.3389/fpsyt.2018.00044/full

(Last reviewed by a Cleveland Clinic medical professional on 01/11/2022.) Cleveland Clinic.  Vagus Nerve. Retrieved 9/13/22 from https://my.clevelandclinic.org/health/body/22279-vagus-nerve

  1. Breit et al. Vagus Nerve as Modulator of the Brain–Gut Axis in Psychiatric and Inflammatory Disorders.  Frontiers in Psychiatry. Retrieved 9/13/22 from https://www.frontiersin.org/articles/10.3389/fpsyt.2018.00044/full
  1. Gerritsen & Band. Breath of Life: The respiratory vagal stimulation model of contemplative activity.  Frontiers in Human Neuroscience. Retrieved 6/25/22 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6189422/

https://greatergood.berkeley.edu/article/item/the_compassionate_species

  1. YouTube: Greater Good Science Center. Dacher Keltner on the Vagus Nerve. Retrieved 9/13/22 from https://www.youtube.com/watch?v=5d6e_Un6dv8
  1. Brooks, et al. Autonomic Control During Pregnancy. Physiology & Pharmacology, Surgery. Retrieved 9/13/22 from https://ohsu.pure.elsevier.com/en/publications/autonomic-control-during-pregnancy-2
  1. Leigh, Suzanne. Stress in Pregnancy Linked to Changes in Infant’s Nervous System, Less Smiling, Less Resilience. UCSF.  Retrieved 9/13/22 from https://www.ucsf.edu/news/2017/11/409146/stress-pregnancy-linked-changes-infants-nervous-system-less-smiling-less
  1. Reyes, et al. Sympathetic Nervous System Regulation in Human Normotensive and Hypertensive Pregnancies. Hypertension. Retrieved 9/13/22 from https://www.ahajournals.org/doi/full/10.1161/hypertensionaha.117.10766 
  1. Hayase, Mako. Shimada, Mieko. Effects of maternity yoga on the autonomic nervous system during pregnancy. Journal of Obstetrics and Gynaecology Research. Retrieved 9/13/22 from https://obgyn.onlinelibrary.wiley.com/doi/10.1111/jog.13729
  1. Seymour, Tom. Medically reviewed by Sampson, Stacy, D.O. Everything you need to know about the vagus nerve. Medical News Today.  Retrieved 9/13/22 from https://www.medicalnewstoday.com/articles/318128
  1. Husain, et al. Pregnancy and delivery while receiving vagus nerve stimulation for the treatment of major depression: a case report. Annals of General Psychiatry. Retrieved 9/13/22 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1242217/
  1. Zheng, et al. Vagus nerve stimulation ameliorates L-NAME-induced preeclampsia-like symptoms in rats through inhibition of the inflammatory response. BMC Pregnancy and Childbirth. Retrieved 9/13/22 from https://bmcpregnancychildbirth.biomedcentral.com/articles/10.1186/s12884-021-03650-7
  1. Lowry, Fran. At-Home Vagus Nerve Stimulation Promising for Postpartum Depression. Medscape. Retrieved 9/13/22 from https://www.medscape.com/viewarticle/974909
  1. Cerritelli, et al. A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows. Frontiers in Neuroscience. Retrieved 9/13/22 from https://www.frontiersin.org/articles/10.3389/fnins.2021.721605/full
  1. Clyde, et al. Transection of the Pelvic or Vagus Nerve Forestalls Ripening of the Cervix and Delays Birth in Rats. Biology of Reproduction. Retrieved 9/13/22 from https://academic.oup.com/biolreprod/article/84/3/587/2530350
  1. Derakhshan, et al. Vagal nerve stimulation for the treatment of male factor Infertility. Andrologia. Retrieved 9/13/22 from https://www.researchgate.net/publication/351268316_Vagal_nerve_stimulation_for_the_treatment_of_male_factor_infertility
  1. Derakhshan, et al. Vagal nerve stimulation for the treatment of male factor Infertility. Andrologia. Retrieved 9/13/22 from https://www.researchgate.net/publication/351268316_Vagal_nerve_stimulation_for_the_treatment_of_male_factor_infertility
  1. Wade, George N. Jones, Juli, E. Neuroendocrinology of nutritional infertility. Regulatory, Integrative and Comparative Physiology.  “The stomach could be yet another site of metabolic fuel detectors that modulate reproduction.” Retrieved 9/13/22 from https://journals.physiology.org/doi/full/10.1152/ajpregu.00475.2004

Page last updated: February 22, 2021.  Polycystic Ovary Syndrome. OASH Office on Women’s Health. Retrieved 9/14/22 from the FAQ titled “What is polycystic ovary syndrome (PCOS)?” at https://www.womenshealth.gov/a-z-topics/polycystic-ovary-syndrome

  1. Linares, et al. Unilateral or bilateral vagotomy induces ovulation in both ovaries of rats with polycystic ovarian syndrome. Reproductive Biology and Endocrinology. Retrieved 9/13/22 from https://rbej.biomedcentral.com/articles/10.1186/1477-7827-11-68
  1. Neuroscience, 2nd Edition. Autonomic Regulation of Sexual Function. Sinauer Associates, Inc. NIH. Retrieved 9/13/22 from https://www.ncbi.nlm.nih.gov/books/NBK11157/
  1. Nestor, James. Breath: The New Science of a Lost Art. Riverhead books. New York. p. 148-150. 

2020. Nestor, James. Breath: The New Science of a Lost Art. Riverhead books. New York. p. 104.

  1. Lin, et al. Breathing at a rate of 5.5 breaths per minute with equal inhalation-to-exhalation ratio increases heart rate variability. International Journal of Psychophysiology. Retrieved 9/13/22 from https://pubmed.ncbi.nlm.nih.gov/24380741/