Crunched: are men to blame for the infertility crisis?
FT data nerds Federica Cocco and John Burn-Murdoch dig into the numbers to discover the real reasons why fertility rates are declining - and ask whether women should really feel pressured by the so-called 'cliff edge'
Directed and produced by Juliet Riddell; filmed by Richard Topping and Joe Sinclair; edited by Richard Topping
Hi. This is "Crunched." And in this series, we're going to look at the numbers behind the biggest news stories and the biggest debates.
In this episode, we're going to be talking about fertility.
If you're a woman like me, over 30, you probably get asked this question all the time, when are you going to have kids? John, do you get asked this question at all?
I can't say it sounds familiar.
Now, I can sort of see why I get asked that question. After all, say 1975, my mum's generation, they would have kids when they were 26.4, that was the average age, and now it's more like 30.3.
OK. But the number that always comes up in these discussions, it's 30, 30, 30, this sort of fertility cliff or something. Now, could it be because of this study that I read, which said that among women in their mid 30s and onwards who are trying to conceive, 67%, about 2/3, successfully got pregnant, but one third didn't. Is that where this comes from?
I've heard of this study, and I found out that it was based on French church records from the 18th century. So you could say we live in a slightly different society now. Back then, people didn't have access to modern health care or electricity, let alone contraception. So you could argue that things have changed.
OK. But then I feel like there's been so many stories still in the news. Like there's always articles on this about 30s and fertility and women.
Yeah, you could say there's been a big government and media campaign about this fertility clip. And I just had a quick look today. Let me show you a couple of articles I've seen.
So there you go. We've got this story. Women's likelihood of getting cancer raised if they're infertile at 30. That's a bit of scaremongering, I would argue.
Half of young women would consider freezing their eggs. And this beaut here, generation of women at risk of infertility epidemic. Freeze your eggs!
So what's going on then? Because this seems to match the study that I saw, but you're saying that this is being blown out of proportion.
Well, according to more recent studies, actually 82% of women are able to get pregnant. This is women aged between 35 and 39 are able to get pregnant in-- within three years. So we're looking at the bar reaching a bit higher.
OK. That seems more reasonable. And how does that compare to women aged a bit younger than that?
That's a good point. For women aged in their 20s, or under 35 at least, it's only slightly a bit higher. You know, not that big of a difference.
[INAUDIBLE] So I guess we're talking about the difference between that and that.
67% of women aged 35--
35 and up.
--and plus, yeah, able to have kids. According to more modern studies, it's more like 82%. And then when we look at younger women, it's just four percentage points higher, 86%.
Yeah. That's hardly a cliff.
Yeah. I would say it's a little fertility dip.
Now John, you said that you never get asked this question about when you're going to have children. But maybe you should get asked, because across all infertility cases, one third are due to the male factor, one third are due to the female factor, and one third, in one third of cases, the cause is unknown. So out of those that are known, it's 50/50 though, isn't it?
Yeah. Since we started talking about this, I-- I've been, you know, having to check the facts for myself. Because at first, I was surprised, but you're right. And so I've been looking at a few stats on this, and ultimately, what this all comes down to is the fact that a lot of studies have now found that male sperm counts and the quality of sperm around the world is declining pretty rapidly.
Yeah, and it's been going on for a while, hasn't it?
Yeah, really long time. So there's a lot of really interesting studies here, and probably the best one was this meta analysis, where in 2016, my researchers looked at 22 different studies from all over the world, from different time periods, and in total, they were looking at data going from 1980 all the way through to 2015. And what they found was that the concentration of sperm per millilitre to get, to use the technical terms, has declined from-- what were we saying here? I think it was from 92 million sperm per millilitre in 1980, and that has fallen to about 37 million in 2015. So that's a huge decline.
Yeah. That doesn't look good.
Just seems obvious that that would have some kind of impact on fertility.
But here's the interesting bit. So scientists in previous studies have also looked at what sort of concentration, what quality sperm needs to be in order to maximise the chances of conception, and they found that the key threshold is at about 60 million. And so the chances of a male successfully fertilising an egg when their sperm concentration is below 60 million parts-- 60 million sperm per millilitre drops, and above that is fine. So we're below that threshold.
Now, the critical threshold people talk about is 20 million. So it's only below 20 million that things that we really have-- let's call this the red zone, where things get pretty seriously bad in terms of chances of conception. So we're not in that critical zone with the 37 million that we currently have.
First of all, this decline is pretty substantial, and if this rate of decline continues, then it would only be about 20, 25, by which point we would be in that red zone. And there's no sign of the decline slowing. And also, yeah, things have fallen, so it's certainly the case that we can't just claim that this is a women's issue.
And do we know what's caused this decline?
So there seems to be a lot of theories. One of them is that it's to do with chemicals in our environment that have been increasing over the last--
I've heard of plastics.
--30, 40 years.
Yeah. So things that can sort of leach out of plastics get into water supplies, that kind of thing. Some people talk about just lifestyle changes. More sedentarism. Just industrialization in general. Essentially, it's not clear, but whatever it is, it's clearly happening.
OK. So to recap. Do a little pie chart. A third of cases, it's the female factor. And another third, it's the men's. Another third, we don't know what's going on.
And what we know, there was a big Lancet study that looked at the number of children that the average woman globally were having, from 1950 to 2017, and this is what they found. In 1950-- gonna do a very rough slope chart-- women were having, on average-- I'm going to get my favourite jelly babies-- having one, two, three, four, 4.5 kids per woman. Now we're looking at two point-- no sensible viewers, sorry-- 2.3.
So clearly, they have declined, right, women are having fewer kids. But is this a fecundity crisis? Does it mean that people are less able to have kids? Are the two things connected? What do we know?
So just to make sure I understand, so we're saying fertility is one thing, fecundity is a different thing. So fertility is just, what, like the number of children people have, whereas fecundity is--
The ability of people I have kids.
So it's a sort of choice versus just biology.
I think what we've seen from a lot of research is this is primarily a fertility issue. So people are simply choosing and living differently in 2015, 2017 than they were 65 years ago, and that's leading to different decisions, different prioritisation, which lead to this reduction [? in unwanted ?] children.
This is what I was saying before, like with the French study, those were different circumstances. They didn't have access to contraception, to health care, to careers, right?
Yeah, absolutely. And it's interesting that you mentioned contraception. So got a little chart here, in true here's-one-I-made-earlier style.
So what we're looking at here is the percentage of births to women aged 15 to 44 in America that were unintended, so unplanned pregnancies, and there's been an 8% fall in that figure just in the last 10 years. So fewer unintended births essentially. So that, for me, is a great demonstration of what we're talking about here.
That-- part of that decline in children is not-- it's not a bad thing. It's simply people have more education, contraception, more ability to actually have the number of children they intended all along.
Right. So women are having fewer unintended pregnancies. They're having the children that they choose to have.
Exactly. Which-- yeah, it's hard-- that's hardly a sort of crisis. That is just people having more control essentially over their life.
And another one, I think this is an interesting stat as well that I found is that we talk about like, you know, how priorities and different lifestyles are having an impact. So in the US, when you look at mothers age at the time of first childbirth, this one was looking at how the age at first childbirth varies according to education. So for women who did not go to college--
So this is in the US.
In the US. There were-- they were on average 23.8 years old at the age of first childbirth. For those who are college graduates, it's 30.3.
So that, you can see obviously, you know, if you're going to college, you're going to be there for several years. That's really going to lead you to postpone childbirth. You're maybe then going into a-- like into a profession where you really want to focus on getting ahead in those first years so this delay of seven years, which often leads to having fewer children as well, is not some crisis of fertility. It's simply women and people in general getting more opportunities to learn, to be educated, and to seek, you know, high status jobs they didn't have in the past.
So what we're seeing here is that this is a result of choices, right? It's not necessarily because women are less able to have kids. So why are these papers talking about an epidemic?
Right. And it's an interesting question. And we can see, again, in the data that this isn't some epidemic. It's not this force of nature, which is just women are sort of victims of, because I've got another chart here, which shows that birth rates in the US to women older than 30 have actually been increasing. So birth rates to teenagers and to women in their 20s have fallen, but in the last 35 years, birth rates to women aged 30 and above have increased. So they clearly are succeeding, even if things can be slightly more difficult. And I know that you were also looking at some of the reasons behind these continued successful pregnancies.
Yeah. And we have something else on our side that French peasants in the 18th century didn't have, which is science. Assisted reproductive technology is now increasingly in use. This is stuff like artificial insemination or IVF. I mean, it's estimated that by 2100, so that's in 80 years time, 400 million people will have been born as a result of ART, assisted reproductive technology.
Right. And it's already happening now. We've seen in the US already, since 2006, so last 13 years, more than one million babies have been conceived and have grown up that were conceived through assisted reproductive technology. And you know, tens and tens and tens of thousands of IVF cycles are now successfully done every year. So yeah, this is happening.
Ooh, and pub quiz question. Do you know which country has the greatest success rate for IVF?
I'm going to say Zambia.
Zambia? No, it's Denmark.
So in conclusion, I think women like me should be really resistant to this language of epidemic and crisis, because as we've seen, a lot of this decline in fertility rates is a result of choices. Not always. Obviously, there is, as we've seen, a fertility dip rather than a fertility cliff.
And also, in some parts, it's also men and then the male factor and declining sperm counts and mobility. So I think men should get asked this question as well. John, when are you going to have kids?