In 2020, my supervisee, Kealagh, was about to submit her PhD, so I asked, as I usually do, “Who would be a good examiner for your thesis?”
The answer was Sheila Crowell, a professor of psychology then at the University of Utah, now at Oregon University. Long story short, Crowell agreed to examine the thesis, which led indirectly to her current research in New Zealand on a Fullbright scholarship. She’s now at the tail end of her six-month visit learning from our local teen parent school.
So much mental health research, mine included, involves young people or adults either at an age when most mental distress emerges or when it has already happened.
Crowell’s reasoning is that we should go back to the source – before that mental distress sets like concrete – and that doesn’t just mean childhood, but even in the womb and just after birth.
Let’s take a step back. What we experience as stress is a natural response to something threatening in our environment. In our evolutionary past, that was things that could eat us. Nowadays, it’s a looming series of work deadlines, worry about paying the bills or living in fear of an abusive partner.
But these things don’t necessarily go away as fast as a toothsome predator – we either get away or, um, get eaten. It’s like a car engine constantly running in first gear – after a while, the engine breaks down and we blow a gasket.
One consequence of chronic stress is a “blunted” physiological response to stress. Basically, your nervous system stops responding effectively to stress, and this blunting seems to predict unhelpful responses when life gets tough – responses such as self-injury.
That stress response has a lot to do with the vagus nerve, an information highway that connects lots of our organs to our brains. It preps your muscles to run, your stomach to stop digesting and other things that help us fight or flee.
Crowell notes that it’s also connected to the uterus – for those of us who have a uterus. So, it’s not a big leap to speculate that maternal stress responses during pregnancy might affect pēpē in utero. But how do you look at this?
When babies cry for attention, they either get it or they don’t, and if they don’t get attention consistently they stop trying.
After all, you keep crying and nobody comes, you risk alerting something that’ll eat you. Quiet keeps you safe. This translates into childhood avoidant attachment, which often translates into adult avoidant attachment – you can’t rely on others, so don’t seek them out.
Normally, when we hear a baby crying, it causes a decrease in our respiratory sinus arrhythmia – increases and decreases in heart rate that are controlled by the vagus nerve.
But remember, chronic or historic stress blunts this activity, so you might not respond to a stressor (like a baby crying) with an adaptive heart-rate response.
Cut to the laboratory, just before baby is born, and Crowell is measuring the respiratory sinus arrhythmia of mothers-to-be in response to a one-minute video of a baby crying. Some mums-to-be show the expected (good) variability in heart rate and others don’t.
The punchline is that if a pregnant woman shows a prenatal blunted physiological response to the video of someone else’s baby crying, seven months later their own baby is more likely to show an avoidant response when Mum ignores them for two minutes. Baby has been sensitised to this in the womb.
Powerful stuff, and a reminder that by the time we need an ambulance at the bottom of that cliff, it’s way too late.
