The Mystery of Childbirth Is Finally Being Unravelled
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Every Sunday, we cover the week's tech news on This Week in Tech. Hi, this is Leo Laporte from the Twit Podcasting Network, inviting you to join me with Jacob Ward, Molly White, and Harry McCracken as we talk about the end of the big lawsuit against Meta and what it means for us. NVIDIA spending lots of money trying to get into the AI software game and real details on that hugging face attack. What you hear will shock you. You'll find it at twit.tv and wherever you get your podcasts.
Today we're discussing one of my favourite examples of evolutionary biology and it's not an insect, it's a human baby.
It's a human baby.
And specifically the drama, the absolute drama that occurs at the birth of a baby.
That is the right way to put it. I can confirm
that
the late stages of pregnancy and the whole business of labour is wild.
Well, I like the idea that there's a battle between the foetus and the mother over nutrition, but also over when to come out, when to get out. And
it's almost shocking, isn't it, to describe that relationship between mother and baby as a battle. But evolutionarily speaking,
that's what it is. Well, they call it the maternal-fetal conflict. But a new discovery that we're going to get into shows that the mother transfers mitochondria to the uterus before birth. And as we know, mitochondria are the power packs of the cells. They're the things that power our muscles, give us energy. And so she does that to power up the muscles of the uterus to kickstart the process of birth.
That's an incredible discovery. And part of that big, big question about what actually calls time on pregnancy and says it's time to get the baby out. And that's what we're getting into today on this episode of The World, The Universe and Us from New Scientist. I'm Dr. Penny Sarshae.
And I'm Dr. Rowan Hooper.
So one thing you may not realize until you have a baby is that the end of pregnancy is this big, uncertain waiting game. So even though you have your due date, realistically, you could expect your baby to arrive somewhere in a month-long period around that
due date. It's
not very useful for planning.
But this is part of the battle, isn't it? Because the baby wants, in evolutionary terms, you know, it wants to stay inside the mother as long as it possibly can. Whereas the mother, the mother's body wants to get the baby out. And the mother's idea of when to give birth doesn't necessarily align with what the baby's opinion on this is.
Why has the trigger for human labour remained a mystery for so long?
And we're going to get into that. But then there's also this mystery of what initiates labor. And for a long time, we really haven't known what kickstarts that process. But now there's growing evidence that it's actually the immune system that presses the go switch for the onset of labor. And what's really exciting about that is because if we know what's actually turning it on, it could potentially give us ways to develop drugs that prevent premature birth, preterm birth. And also maybe to even predict exactly when you are likely to have that baby.
Wow.
So to talk about this, we're joined by Alice Klein, who also has first-hand experience of waiting for babies to come out. And she's been reporting on this new finding. Alice, why has it taken us so long to work out what actually triggers labour? And why has there been such a mystery around it?
Well, basically a lot of what we know about the labor process comes from studying other animals like mice and sheep. And in most of them, the trigger for labor is pretty simple. When the baby's finished growing and ready to come out, the pregnant female stops producing a hormone called progesterone. As this hormone drops, it tells the genes needed for labor to turn on, and then that gets things moving. But in humans, progesterone levels in the blood don't actually fall when labor starts. So that's something that has really perplexed scientists for a long time.
And so also humans walk on two legs and sheep and mice walk on four. So we're going to get into that,
that
whole aspect of it. But this new research then suggests that in humans, it's the immune system that activates labour.
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Chapters
8 chapters
1
What is the main topic discussed in this episode?
0:00–2:27
2
Why has the trigger for human labour remained a mystery for so long?
2:27–5:50
3
How does the immune system initiate the onset of labour?
5:50–9:32
4
What role do inflammatory macrophages and mitochondria play in kick‑starting birth?
9:32–13:23
5
How could this new immune‑based discovery help prevent pre‑term births?
13:23–16:11
6
Can a blood test predict when a woman will go into labour?
16:11–19:23
7
What is the ‘obstetric dilemma’ and how does bipedal evolution affect childbirth?
19:23–21:15
8
Why are human babies considered altricial and is the fourth‑trimester myth real?
21:15–21:51
Speakers
4 identifiedMore from The World, the Universe and Us
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