Globally, one in every 42 children is born a twin. According to a study analysing birth records from more than 100 countries, this is an increase of a third over the past 40 years. But the trend is now moving downward. So have we reached “peak twin”? I spoke to the study’s author, Christiaan Monden from the University of Oxford.
What does “peak twin” mean?
It means we’ve reached a point where we’ve seen or are seeing the maximum number of twins being born in the world, and that the number will ultimately go down. That’s what we mean by twin peaks – sorry, peak twin.
I keep saying “twin peaks”, too, but that’s a David Lynch series. Although in a way, lots of twins suddenly being born is quite strange. Trippy, perhaps Lynch-esque. But I digress! Is the global peak mostly because of Europe?
We’ve always seen higher twinning rates in Africa. That’s genetic. But with the introduction of IVF in western Europe, the US and countries such as Australia and South Korea, the twin rates have risen more widely. Those trends are now reversing as IVF regulators have been changing their policies to get the twin rate down because of the increased health risks associated with twin pregnancies.
How?
With IVF, you have to make a decision: how many fertilised eggs do you transfer back into the mother? You want at least one of them to survive, so you have more of a chance if you transfer two or three eggs – but if they all survive, they become twins or triplets. In the early 90s, only one in eight women had a single embryo transferred, but now three-quarters do, still with the same success rate because over the years IVF has improved.
So have we lived through some sort of historical blip where we have a lot of twins, and it will never happen again?
Yes. Unless some other fertility treatment comes up that has a similar impact – which is extremely unlikely – this won’t happen again.
Perhaps it should if all the headlines about Britain’s baby shortage are to be believed.
The fertility rate has been going down very slowly, yes, but IVF numbers will still increase. So I’m not worried. We’re not in the position of some countries with ultra-low fertility. We don’t want to go there – not because there are too few of “us” on the islands, but because low rates might indicate people don’t have the conditions, both financial and social, that allow them to achieve their desired number of children.
I hear you on the dog-whistle nationalistic undertones of some population discourse. But then there’s the economics. We have an ageing population.
That’s a bit gloomy. Very few pro-natalist policies have worked, by the way. If you give someone cash for a baby, they don’t have more children, they just have the ones they wanted, earlier. And when pro-natalist policies promote nationalist ideas, it doesn’t help increase our quality of life. But we do need to think about how we stay productive for longer.
Robots! Keeping with the Lynch theme …
Yes! There are more important things to focus on than too few humans. We should focus on the quality of life, not on the quantity.
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