Centering around pregnancy, Part Three: What does this have to do with stress?
If pregnancy = the physiological edge, then stress = the extra push. Is that push avoidable?
Wrapping up the series on why the maternal stressor map centers around pregnancy with… STRESS!
This post is a continuation from Part Two. I highly recommend starting there if you’re catching up:
And if you want to go all the way back to the beginning, Part One is here:
OR you can also just skip over all of the science-y stuff (there is A LOT) and head to the bottom of this post for the big “So what?!” of it all.
Choose your own adventure!
To summarize Part Two:
Pregnancy is both natural and risky – It is normal for a body to undergo all the extreme physiological changes needed to grow and birth a human being with no medical intervention AND it is normal for a body to undergo all the changes, be pushed too far, and require clinical support. Maintaining homeostasis — the biological balancing act related to health — during this life event is tricky.
With all the extreme physiological changes related to pregnancy and postpartum, we need to consider how this normal, natural life event can sometimes tip the body out of homoeostatic balance, and lead to illness. Not all pregnant bodies will tip. Most won’t. But all pregnant (and postpartum) bodies are closer to tipping.
Which is where stress comes in.
Where stress comes in…
To reiterate an important point for the discussion ahead:
Pregnancy is NOT a stressor1. Postpartum return is NOT a stressor. Lactation is NOT a stressor. And none of these states represents illness. These are natural processes in the human body that sometimes tip that body off balance, naturally, and lead to illness.
For how I’m defining stress and stressors, revisit this post:
Ok, I’m done assigning homework, I promise!
Back to Part Two’s explanation of homeostasis — every up has a down to counterbalance and maintain a steady state — and the body’s response to challenges:
All the systems in our bodies (think cardiovascular system, metabolic system, immune system, etc.) have a normal range of set points. All the mediators and modulators within those systems work together to keep that system balanced within a baseline range that is key to sustaining life.
There are other ranges that relate to how the body responds to challenges. There is a range related to responding to predictable challenges. There is a range related to responding to unpredictable challenges.
Baseline = sustaining life
Predictable challenge = normal, necessary daily activity.
Unpredictable challenge = an acute stressor.
In Part Two, we used glucose regulation as an example of how the body works at baseline and responds to a predictable challenge. In that context, a predictable challenge is eating a meal.
In the context of an unpredictable challenge, we’ll go all the way back to the evolutionary reason why our stress response system works the way it does to begin with – survival in the face of danger (or potential danger).
Unpredictable challenge = a lion trying to eat you (or a modern-day lion).
(Quick note: I’m going to build on the glucose regulation example of the last post).
You, as a distant human ancestor, spot a lion quietly stalking you. Once the brain perceives the stress of a predator threat, the signal goes out to run away or fight. You will need a quick release of glucose to your muscles for power and signals to stop insulin from packing it away. A high blood sugar spike is “good” in this scenario.
Everything regulating blood glucose responds to that acute stressor in an adaptive way. The effect on blood glucose and insulin is dramatic but quick – turning on quickly, shutting off quickly. Stressor passes, stress response clears out. Most importantly, the stress response occurs far more rarely than the predictable response to food consumption.
Well, it occurs more rarely in the context of predators on the savannah. We modern day humans respond to modern day lions. And there are far more modern day lions in our world than our bodies have adapted to on the savannah. As a result, we, modern-day humans, have a tendency to abuse the stress response system and push it beyond its normal working capacity.
When the system is pushed beyond its normal working capacity (= chronic stress), all the factors that keep homeostatic balance are no longer able to do their job in an effective, survival-focused way. Pummel the bloodstream with stress-induced glucose spikes while tampering with insulin function and you walk away with insulin insensitivity and high blood sugar. And this is why Type 2 Diabetes can be associated with stress.
Similar thing with gestational diabetes. The pregnant body is already primed for insulin insensitivity. Some bodies may go over the physiological edge without any additional push (as discussed in Part Two). For others, the push over the edge comes when glucose levels and insulin respond to stress on top of the normal pregnancy-related changes.
The stress response system stimulates and/or exacerbates pathological outcomes related to pregnancy, birth, and postpartum.”
In summary, the body, during pregnancy and postpartum (and likely, other periods of physiological flux), is especially vulnerable to stress-related illness because, naturally, it is closer to tipping. And there you have the perfect storm — alignment of a time in life when stressors are more numerous and the stress effects on health are more potent.
Seesaw analogy time2!
If homeostasis during pregnancy and postpartum resembles building and disassembling a house of cards on a seesaw:
Then stress is the extra weight on that carefully balanced seesaw.
This extra weight might load on during the construction of the houses of cards or pile on when the body is attempting to delicately disassemble it. Not ideal in either case.
A body internally closer to tipping does not need additional external factors working to tip it.
A few examples of how this might relate to health outcome research:
Inflammation and PPD
New research has started making connections between peripartum depression (PPD) and immune system shifts in the inflammatory response across trimesters.
“If you look at the ways their immune systems change, it’s not so simple as saying there’s more or less inflammation. It’s that there’s this dysregulation all over.” – Lauren Osborne, vice chair of clinical research in the department of obstetrics and gynecology at Weill Cornell Medicine, as told to the Washington Post.
The immune system during pregnancy is truly the contortionist in the three-ring circus that are the physiological changes during pregnancy. The immune system flips itself between inflammatory and non-inflammatory — facilitating implantation (inflammatory), ignoring that parasitic creature growing inside the body (non-inflammatory), and then acting as a buddy to uterine contractions (inflammatory).
Inflammation has also been linked to depression. With new research showing that dysregulation of the immune system and inflammation during pregnancy may underlie the most serious cases of PPD. There is also evidence that a failure to return certain immune cells to pre-pregnancy functionality may facilitate PPD.
These studies are exciting but the research is in early days so the timeline to new diagnostics and treatments are still far off. We still don’t know how all the cards are stacking or even which cards get stacked. And we don’t know which cards are the weak links.
We do know that the cards need to stack for a healthy pregnancy (these immune changes are key to maintaining a pregnancy) but we don’t know how to target individual cards to prevent tipping (dysregulation and illness).
AND, we do know that stress is linked to inflammation and that is especially bad during this window of time.
While we wait for the research to catch up, here is what we can do today – Limit stressors. Do not add more weight onto this seesaw.
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Gestational diabetes and PPD
Across various research studies, there appears to be a connection between gestational diabetes and PPD. This connection is different than the immune system → PPD link discussed above. It is not that glucose intolerance related to gestational diabetes is affecting the brain. It’s more likely related to all the other stuff going on during this time of life. And the data are messy.
In the mumbo jumbo language of academic writing from a 2019 meta-analysis of every reasonably strong study (18 in total!) investigating the links between GDM and PPD:
“The present study showed that GDM increases the risk of PPD.... Although there are some preliminary studies in this area, no final decision has been made on the association between GDM and PPD. In this study, considering the systematic review of all documents and their combination through meta-analysis, this relationship was investigated, and the existence of such relationship was indicated.”
The authors go on to say:
“the possible mechanisms that justify the association between GDM and PPD can be the disturbance of the hypothalamic–pituitary–adrenal axis, inflammatory changes, disorders in serotonergic regulation, the effects of hyperinsulinemia on the thyroid and the mental stress caused by the treatment of chronic disease” – Azami et al. 2019
I read these statements as, “Ok, these things seem connected. We don’t know why these things are connected. Pregnancy messes with a lot of systems. Maybe blame stress?”
This makes sense to me – stress can underlie gestational diabetes and stress can underlie PPD. And then factor in the stress of getting the diagnosis, being told that you have to change your diet and your life in order to have a healthy baby, and that any negative outcome might be all your fault. That stress may relate to PPD. As more research is conducted, maybe we’ll get a more solidly-backed view on the connection.
Again, research has not connected all the dots BUT we do know that stress (even in the form of clinical delivery, lack of support, and overall mom guilt) is bad during this window of time.
While we wait for the research to catch up, here is what we can do today – Limit stressors. Do not add more weight onto this seesaw.
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Stress —> weathering and increased risk of maternal mortality/morbidity
The interaction between stress and the physiological flux of pregnancy/postpartum is also key to considering health risks associated with a lifetime of stress-related wear-and-tear and weathering. (see section on wear-and-tear and weathering in the Stress 101 post).
In these cases, the impact of stress exposure comes before pregnancy. Here we have a seesaw that has already experienced wear-and-tear and consistent life-time stress on the system. The board itself has weakened under the constant weight.
Adding in physiological changes during pregnancy and postpartum is essentially building and deconstructing the house of cards on board that is already closer to tipping and breaking due to that lifetime of wear-and-tear.
Weathered bodies enter pregnancy at a different baseline, a different level of load, and then they are exposed to even more severe stressors during this window of time. This is likely why Black women, exposed to the weathering effect of racism in America, are more at risk for perinatal health concerns (e.g. cardiovascular diseases) and negative birth outcomes (e.g. preterm birth), and experience the highest maternal mortality rates in this country. Even the healthiest of the healthy have a higher risk.
And while we wait for the research on those gaps, here is what we can do today – Limit stressors. Do not add more weight onto this seesaw.
Maybe you’re sensing a trend here.
Which brings us to…
Pregnancy and postpartum physiology are understudied. Moments of physiological flux at other times of life – e.g. perimenopause and menopause – are even less studied. I expect with more research in these areas, we’ll start to see a similar scenario as it relates to stress. We may even see similar small windows of vulnerability across the menstrual cycle… when and if that topic finally gets its due.
We need more research.
We need to study the cycling body, the pregnant + postpartum body, the perimenopausal + menopausal body, and the weathered body a WHOLE lot more in order to make the direct connections between stress, physiological flux, and health.
There are many critical pieces missing in the gappy gappy puzzle that is the field of Women’s Health. And while I am thrilled that these gaps are finally getting national attention and funding, I’m going to stay realistic about what this attention and funding means for us, today….
It means nothing.
Here is the reality: Applying and getting funding takes time. Research takes time. Clinical adoption takes time. Medical innovation takes time. Drug development takes time. Adding all this up, wishful thinking puts timing for impact around the day my daughters and their peers start having babies or their babies have some babies (my girls are currently 8 and 10).
While I love considering the long-term impact of this funding announcement, I am not optimistic about the near term impact of it. But my pessimism is what is fueling this project. Because we all deserve to be healthy NOW.
If we look at the physiological data we do have today, we can see and build an evidence bank to demonstrate how decreasing the stress related to modern American motherhood (especially at moments of physiological flux), will have short- and long-term health impacts.
When it comes to stress, again (and again and again), the individually-focused stress management advice of ‘nap, meditate, exercise’ is not going to broadly impact women’s health. Impacting health will happen when we address key stressors and their connections. When we fix broken systems and create cultural shifts. When we get much needed structural support and culturally competent care. When we finally acknowledge that societal issues affect our health. When we respect solutions operating on the subclinical level of stress buffering and mitigation as preventive healthcare.
Clear problems but, also, clear solutions.
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If this statement irks you, you are in good company. I have a bonus post coming up where
and I debate this statement and the language behind it.Bonus Post: Is pregnancy itself a "stressor"?
I know this is NOT a perfect analogy. It’s a work in progress. Poke some holes and challenge it, please!