A tale as old as time… or, at least, somewhere as old as the existence of a couple of guys by the names of Ballantyne and Runge, who made separate observations about babies who were born appearing underdeveloped, malnourished and otherwise unwell. Ballantyne first, followed by Runge, whose combined observations began to be known as Ballantyne-Runge syndrome and was theorised to be the result of placental insufficiency associated with “over-gestating”.
This theory has been around since the 50s and is therefore well ingrained in maternity care.
The trouble is… theories are not facts.
Placentas are not like, to borrow a metaphor from Dr. Sara Wickham, pumpkins: doomed to magically transform at the final chime of midnight on woman’s arbitrarily determined ‘due date’.
Dr. Wickham writes in her book Inducing Labour, making informed decisions: “The concern here is that the concept of placental insufficiency could be described as rather ‘slippery’, and there is no evidence to suggest that there is a correlation between placental insufficiency and length of pregnancy. As an obstetrician friend of mine likes to say, if a woman’s placenta isn’t working well at 23 weeks, then it is unlikely to be working well by 39 weeks. But if it is working well at 40 or 41 weeks then there’s no good reason to think its function is suddenly going to decline over the next few days.”
She explains that sometimes, indeed, placentas do start to fail, but that we have no evidence to prove that this happens either routinely or at a certain cut-off point.
Dr. Sophie Messager has written an impeccable article titled “The Myth of the Aging Placenta” that I would highly encourage reading if this is a topic you wish to understand more about. Her PhD in reproductive physiology alongside her background as a doula and birth educator makes her the perfect person to delve through the evidence on this topic.
From the outset, she makes a very important observation that science is NOT black & white and even experts will often disagree with one another, and that good scientists know and understand this. That anyone suggesting to have guarantees or all the answers when it comes to science is being foolish, at best.
Dr. Messager discusses the concept of growth and maturation of the placenta, compared with the idea of “aging”, which seems to connotate with insufficiency. She shares that even the research that does claim a link between gestation and placenta function are still only concluded as “’possible’ rather than “proven”. She pulls apart some of the commonly referenced biological changes given as evidence of a placenta aging towards insufficiency and explains what these different processes are in laymen’s terms as well as why there is plenty of reason to assume these changes could just as easily be considered growth and maturation phases, not only quite physiologically normal for the placenta, but even critical to its function.
Another commonly discussed issue used as evidence for the aging placenta is calcification.
Billie Harrigan writes an excellent blog post on this topic, with her references clearly outlined.
What she explains is that in term (39+ weeks) placentas, calcification can be considered completely normal:
“One of the features of a Grade III [39wk+] placenta is that it often shows circular indentations that have calcium deposits (calcification). This is considered to be a natural part of the aging process in much the same way that our skin develops wrinkles as we age. And just as wrinkles in the skin of a person of any age doesn’t mean that this person is at risk of imminent death, neither does the appearance of calcification in a normal placenta at term mean that it’s about to expire (Harris & Alexander, 2000; Jamal et al., 2017; Nolan, 1998)”
However, early calcification of the placenta can be indicative of a problem, which is probably where this idea of calcification being dangerous develops from.
Women should carefully consider a recommendation for an induction given at term due to an “aging placenta” when they and their baby are otherwise well, if for no other reason than a baby who is considered to be at risk from an insufficient placenta should not be undergoing the stress and duration of an induction anyway, but should be born immediately by caesarean. It’s something of a contradiction to suggest that a baby might not be growing well and then recommend an induction of labour to resolve that when an induction is known to increase the risk of fetal distress and can takes days to get moving.
And if that contradiction isn’t enough for you, what about the absurdity of the fact that the other main reason otherwise healthy women and babies are recommended induction at term is because their babies may grow too big? Obviously inherently contradictory to the idea of an aging, inadequate placenta - a baby who manages to grow “too big” would need a lush, healthy, nourishing placenta.
“There is, in fact, no logical reason for believing that the placenta, which is a fetal organ, should age while the other fetal organs do not: the situation in which an individual organ ages within an organism that is not aged is one which does not occur in any biological system.” Prof Harold Fox, Aging of the Placenta
In essence, the issue we have is that of an unexplained increased risk of stillbirth (that is still a very rare occurrence) in late term and postdates pregnancy and a desperate desire to find an explanation and solution. It’s understandable that clinicians jump at the opportunity for such an explanation and solution - if this was demonstrably saving babies’ lives, we’d be having very different discussions. However, the theory that the rise in stillbirth can be accounted for by aging placentas is only a theory with no good evidence to back it up.
The idea that mothers should be induced to avoid their placenta aging also relies on the idea that delivering babies early, either via induction of labour or caesarean section, is without risk… and it isn’t. In fact, more and more research is undertaken and released all the time showing us more potential risks of induction - check out this study released 2021 by Australia’s own Prof Hannah Dahlen. As for caesarean, I don’t think anyone would suggest that major abdominal surgery is risk-free.
We come back to what should be the basic principles of maternity care - that women should be adequately and accurately informed of the risks and benefits of all their options and supported to make the decisions that are best for them.
Sources and Further Reading:
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This blog article was originally written for the Doula Training Academy
My name is Katelyn Commerford and I am a doula and next birth after caesarean guide who has completed comprehensive doula education at Vicki Hobbs’ Doula Academy. If you want to know more about what I do and how I can help you, please visit my website where you can get your free cheat sheet of my favourite VBAC resources, or find me on instagram @thenbacguide where I answer commonly asked questions about planning the next birth after caesarean and share loads pregnancy, birth, postpartum and parenting content.
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