Our latest Freakonomics Radio podcast is called “Misadventures in Baby-Making.” (You can download/subscribe at iTunes, get the RSS feed, listen live via the media player above, or read the transcript.) What’s it about? In a nutshell: for many years, we’ve been wowed by new technologies and policies meant to make childbirth a safer and more manageable enterprise. But, as always: beware the unintended consequences.
Given that the world’s population is approaching 7 billion, we begin the episode with a look back at another landmark moment in population history. In the late 1970’s, as we moved past the then-unfathomable 4 billion mark, scientists were trying to get a handle on population growth. In the Netherlands, Geert Jan Olsder, a math professor at the University of Twente, co-wrote a paper called “Population Planning: a Distributed Time-Optimal Control Problem,” in which he imagined an island nation with no emigration or immigration – just births and deaths. The essential riddle was this: as the population aged, and as longevity increased, what was the right birth rate to prevent the island from becoming overpopulated? Olsder came up with an elegant equation to describe the solution. Not long after, he shared this paper with a Chinese scholar who happened to be visiting the university. Olsder could never have predicted the repercussions of that chance encounter:
OLSDER: I did not realize at the time, but now that I look back and I see what the consequences were, I think that [the Chinese scholar] was triggered by this kind of scientific work. And of course he was “just” a domino in a long series of dominoes. And maybe I was also a domino, and they all started falling. And ultimately, of course, the consequences were the one-child policy in China.
This Chinese scholar, Song Jian, went on to be one of the architects of the one-child policy back home.
That story is just the first of four stories that Dubner tells in the episode. You’ll also hear how the introduction of the ultrasound machine in Asia has had a dramatic effect on gender selection. We interview Mara Hvistendahl, author of Unnatural Selection: Choosing Boys Over Girls, and the Consequences of a World Full of Men, which examines how the ability to sex-select using the ultrasound led to the disappearance of an estimated 160 million females in Asia alone. (Amartya Sen wrote about this problem in 1990 when the number was 100 million.)
What are the consequences of a world with way too many males? More sex-trafficking, higher levels of AIDS, and a higher crime rate, to name just a few. In fact, Hvistendahl reports, the best predictor of a high murder rate in parts of India is to look at the sex ratio in the region.
You’ll also hear Steve Levitt talk about his controversial research with John Donohue that linked the passage of Roe v. Wade to the falling crime rate. The idea came to Levitt one day in the library as he leafed through the Statistical Abstract of the United States.
LEVITT: I saw that there were only about three million live births in the United States each year. And I thought to myself: One million abortions and three million live births. That means one out of every four pregnancies is ending in abortion. That just seemed shocking to me. And I thought to myself, That’s got to affect something.
Finally, we talk to Stanford researcher Stephen Quake about a new blood test that can help pregnant women learn if their babies are likely to be born with Down Syndrome. This leads to yet another moral dilemma in baby-making: as parents can learn more and more about what’s in the womb, what kind of decisions will they make? And what will the consequences be decades later?
Misadventures in Baby Making
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Geert Jan OLSDER: Ok, my name is Geert Jan Olsder, last name is Olsder spelled as O-L-S-D-E-R. My age is sixty-seven, which in the Netherlands means that you are retired.
Stephen J. DUBNER: Before he retired, Geert Jan Olsder was a university professor in applied mathematics. In 1975, Olsder was 31 years old. He and his colleagues at Twente University were very bright. They thought they could do… anything.
OLSDER: It simply popped up suddenly: why don’t we work on population planning?
DUBNER: Of course: population planning! What else should a mathematician be working on? Olsder’s crew imagined an island nation with no emigration or immigration – just births and deaths.
OLSDER: It looked like a nice mathematical problem.
DUBNER: The essential riddle was this: as the population aged, and as longevity increased, what was the right birth rate to prevent the island from becoming overpopulated? Olsder and his colleagues worked hard on the problem, and they came up with an elegant equation. Their research paper, called “Population Planning: A Distributed Time-Optimal Control Problem,” was published in a university report. One day, Olsder was in his office with a colleague…
OLSDER: And then we got a telephone call from the central, or main office of the University and they said, Oh we have a group of Chinese people here, scientists, and apparently something went wrong in the organization, we didn’t know about this group coming, but they would like to be entertained this afternoon. And there are two mathematicians among them. Would they be welcome in your department?
DUBNER: Okay, so there were a few visiting Chinese scientists on campus who needed babysitting. Would Olsder take care of one of them? Sure, he said. He took him to a café; they ordered beers. They chatted about the university, about the math department …
OLSDER: But after one hour, or maybe one and a half hour or so, the conversation stopped somewhat, because I don’t know from lack of interest, I don’t know, but, but...
DUBNER: Tell me, how did the conversation turn to the topic of your paper about the mathematics of population?
OLSDER: That took a while, because in the beginning we were talking in general terms. I hesitated at a moment, shall I talk about this population planning paper?
DUBNER: Olsder hesitated because his paper had to date only been published internally. He didn’t want to risk getting scooped by another scholar. But – well, math is math and beer is beer, so Olsder told this Chinese guest about his population paper.
OLSDER: He took a lively interest. I mean, it seemed as if he thought at that moment already that it might be something for us. I did not realize that at the time, but now that I look back, and I see what the consequences were, I think that he was triggered by this kind of scientific work. And of course he was just, “just,” I mean between parentheses, a domino in a long series of dominoes. And maybe I was also somewhere a domino quite in the beginning and they all started falling. And ultimately of course the consequences were the one-child policy in China.
DUBNER: The one-child policy in China... hatched over a beer? Who knew?
ANNOUNCER: From WNYC and APM, American Public Media: This is FREAKONOMICS RADIO. Today: Unplanned Parenthood: Misadventures in Baby Making. Here’s your host, Stephen Dubner.
DUBNER: 1975. Two strangers, one Chinese, one Dutch, talk shop over a beer and, when the conversation stalls, the Dutch mathematician mentions a paper he’s written on population control. Hmm, says the Chinese visitor. Might you be willing to mail me a copy of your paper? Sure, says the Dutch professor. Tchin-tchin!
What Geert Jan Olsder didn’t know was that his visitor, Song Jian, was a leading Chinese government scientist. His background was in missile science, but his research portfolio now included population control. In fact, he would go on to become one of the architects of the one-child policy that China introduced in 1978. And he later credited Olsder’s research as an influence. Now, it’s not as if the one-child policy wouldn’t have happened had those two men not met back in Holland – but it’s still pretty sobering to consider the unintended consequence of that chance encounter over a beer:
OLSDER: I was this butterfly who moved its wings, you know, and that causes a fly to move, and then you get a little pebble that moves, et cetera. And ultimately you have a hurricane. Maybe I was one of the starters of this process, but purely by accident. And no, I couldn’t have realized at the time, so I mean, if we could redo history, probably the same would happen again. You feel flattered of course if people take an interest in your research. My feelings about these consequences, I mean, how should I put it, some people ask me ‘Do you feel guilty?’, but I think that’s not the right question. Because, I mean, the same could happen again nowadays under the same circumstances.
DUBNER: The one-child policy that Olsder’s research helped inspire is thought to have prevented roughly 250 to 300 million births in China since 1980. And given what you remember from biology class, you’d probably think that those never-born kids would be about equally divided between boys and girls, right?
Mara HVISTENDAHL: In most human populations, the natural sex ratio at birth is around a hundred and five boys for every a hundred girls.
DUBNER: What is the most accepted explanation for why that ratio exists?
HVISTENDAHL: You know, it seems to be nature’s way of insuring a balanced population later on, because it turns out males die at higher rates throughout their lives. And so by the time we reach adulthood we have an equal number of males and females.
DUBNER: That’s Mara Hvistendahl. If you’re keeping score at home, that’s H-V-I-S-T-E-N-D-A-H-L, cause she’s originally from Minnesota.
HVISTENDAHL: I’m a Beijing based correspondent with Science magazine, and the author of “Unnatural Selection: Choosing Boys Over Girls and the Consequences of a World Full of Men.”
DUBNER: When Hvistendahl first moved to China, in 2004, she noticed something strange.
HVISTENDAHL: The fact that you could go to a school and look at a classroom, an elementary school usually, and you just see many more boys than girls.
DUBNER: And what did you do about it at first? Did you talk to the principal or the teachers and say, ‘Hey what’s going on? Are the girls being kept at home?’ Or did you kind of know right off what was going on?
HVISTENDAHL: Well, it crops up in the news from time to time that sex-selective abortion has become very common in China. So that when women are pregnant, they get an ultrasound exam, and if the fetus turns out to be female, they abort. That’s not all women by any means, but enough that there’s a pretty significant gap in male and female births. So, that appears in the news every time a new census comes out, or a new survey, you see another article, and the Chinese press reports on it as well as the foreign press. But the reasons why that gap existed aren’t typically very well explained.
DUBNER: So for people who are aware of what are called the “missing women problem,” probably most of them are aware of that in large part because of I guess a paper that Amartya Sen wrote years ago, right?
HVISTENDAHL: Mm-hm, 1990.
DUBNER: Okay, and so kind of state for me his argument as best you understood it coming into moving to China.
HVISTENDAHL: Well, Amartya Sen looked at the total number of women in Asia and compared it against the number of women that should be there if the continent had a natural sex ratio. And in 1990 he found that there were a hundred million women who were missing, who hadn’t been born, but who should have been born. The natural sex ratio tells us that they should have been there. And he wrote a paper for The New York Review of Books just pointing out this gap, and the fact that this has happened at a time when China and India and other countries in Asia are developing very quickly, and really to say that we have to consider this when we look at development and women. And the fact that these countries are moving ahead and yet women are disappearing should be really worrying for us.
DUBNER: Hvistendahl found that the overall boy-girl birth ratio in China is 121 boys for every 100 girls. In one city, Lianyungang, the ratio was 163 to 100. And it wasn’t just in China. In India, the overall ratio was 112 to 100. According to one estimate, there are now more than 160 million missing women throughout Asia. That’s about the same size as the female population of the U.S. Now, this gap is surely not all the result of sex-selective abortions. There’s a lot of fatal violence against girls and women; girls tend to have worse economic and educational and medical opportunities. But still: no one can deny that in a lot of places, new parents have an overwhelming “son preference.” Now why? There are probably a lot of reasons: male children carry on the family name… they’re considered more valuable to the parents, because they can perhaps provide for the parents later in life… So I asked Hvistendahl: is this decision typically an economic one?
HVISTENDAHL: You know, not entirely economic. I think there may be a more emotional reason as well. In my book I actually don’t go into these different reasons so much, because I was really interested in how you get the same trend of many more boys being born than girls in this very wide variety of cultures. More boys than girls are born in China, India -- also South Korea, Taiwan, Azerbaijan, Armenia, Albania, Vietnam, and you know there are places that have very different political traditions, some shared religions and cultures, but there’s nothing that really binds them all together.
DUBNER: Nothing that binds these countries together except for maybe one piece of technology, yes, one piece of medical technology?
HVISTENDAHL: That’s right
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DUBNER: Coming up... One piece of technology. 160 million missing women.
HVISTENDAHL: In some countries, where sex selection has taken off, people see this machine as really a way to ensure them a boy.
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ANNOUNCER: From WNYC and American Public Radio, this is FREAKONOMICS RADIO. Here’s your host, Stephen Dubner.
DUBNER: As we know, an ultrasound machine can be used to monitor a fetus in the womb to make sure the pregnancy is coming along all right. But since it was introduced in Asia in the 1980s, the ultrasound has also been widely used to determine the sex of a fetus -- and, if it’s a female, have an abortion. Over the past half-century, the female-to-male gap in Asia has more than tripled. As Mara Hvistendahl tells it, this has changed how people view the ultrasound machine:
HVISTENDAHL: I visited an office of the Family Planning Commission in Anhui Province in China, and the Family Planning Commission is the entity that enforces the one-child policy. Today they are actually tasked with dealing with the sex ratio imbalance a little bit as well. So, they were talking to me about what they’re doing to ensure that people have more girls, and the various efforts that they’ve been taking to make sure that the technology’s used in the proper way. And they showed me to the room in their office where the ultrasound machine’s kept, and they had actually installed two locks on the door. And no employee was allowed to possess the key to both of them at the same time. There were two doorknobs and it was called the two-lock system.
DUBNER: And the idea being that you need two separate employees to unlock these doors, to use the ultrasound under what conditions then? Under what circumstance then is ultrasound use okay in this office?
HVISTENDAHL: Well, it’s illegal in China to use ultrasound to determine the fetus’s sex. So the idea being that if there’s some oversight and two people are in the office at the same time, that they will somehow avoid breaking the law. I don’t know if it works in practice, but what it suggests it that the ultrasound machine is viewed as a dangerous thing.
DUBNER: So what happens in a world with a surplus of men? For starters, there’s more sex-trafficking, more AIDS, a higher crime rate. In fact, if you want to know the crime rate in a given part of India, one surefire indicator is the gender ratio: the more men, the more crime. Now, you might assume that sex-selective abortion is a plague of the lower classes, where the economic penalty of having a girl might have the most sting. But that’s not what Hvistendahl discovered:
HVISTENDAHL: It’s high-income people who have access to new technology first, so when the ultrasound machines arrive, they are the first to use them. But at the same time also the birth rate has fallen pretty dramatically among upper classes and among educated people. So, when the birth rate drops, that puts pressure on a woman to make one of her two or three, one children a son.
DUBNER: As it turns out, there’s one particular kind of parent for whom this son preference is overwhelmingly strong. These are parents who are having a third child when their first two are daughters. In such cases, among these parents, sons outnumber daughters by 50 percent. And who are these parents? They’re Chinese, Korean and Indian parents – who have emigrated to the United States.
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DUBNER: Now, the ultrasound machine didn’t create this kind of problem, but it does enable it. “Son preference” already existed, but along came a new birth technology that let mothers do something about it. Technology has consequences – often unintended ones. So do laws.
Steven D. LEVITT: So, probably the most controversial finding that I’ve ever had in economics was the argument John Donahue and I made that legalized abortion led to decreases in crime.
DUBNER: That’s my Freakonomics co-author Steve Levitt. He’s a research economist at the University of Chicago. He was in the library one day, just leafing through the Statistical Abstract of the United States...
LEVITT: And I was shocked to see the number: a million abortions a year. And I thought to myself, you know, a million of anything is a lot, but abortion. I never would have imagined that abortion was so prevalent. But I didn’t really have any sense of the scale, so I thought well how many births are there? And luckily this book had everything in it. So, I flipped a few pages forward, and I saw that there were only about three million live births in the United States each year. And I thought to myself one million abortions and three million live births, that means one out of every four pregnancies is ending in abortion. And that just seemed shocking to me. And I thought to myself that’s got to affect something.
DUBNER: Abortions spiked in the U.S. after Roe versus Wade, the 1973 Supreme Court decision that made abortion legal in all 50 states. As Levitt thought, a number that big – one million abortions a year, one out of every four pregnancies – that’s got to affect something. Now, he’d spent the past several years doing research on crime. His mind immediately mashed up his old research topic with this new one.
LEVITT: So, what does this legalized abortion have to do with crime? Well, the argument’s really simple, that there’s enormous volumes of scholarship going back fifty years that suggests that unwanted children are at risk for crime. Basically if your mother doesn’t love you, nothing very good is going to happen to you in your life. It’s also pretty clear that after legalized abortion became available, the number of unwanted children plummeted, so we see that the number of domestic children put up for adoption went way down. And in surveys, if you ask women whether they had unwanted births, those went way down as well. So, those two simple pieces of the argument are all it takes. Unwanted children are at risk for crime, and after legalized abortion the number of unwanted children went way down. Therefore, after legalized abortion, crime should go way down if you wait sixteen to eighteen years to the point where that cohort exposed to legalized abortion actually becomes old enough to be in the criminal ages.
DUBNER: That was the theory, at least. And as Levitt found, the data backed it up: Roe v. Wade, a decision meant to increase a woman’s reproductive control, was never intended to decrease crime in the U.S. But it did! Again, like the ultrasound, a natal development that had the most unintended of consequences. So you have to wonder: what’s next? What’s the next baby-making law or technology that we’ll be talking about in 20 years? And who’ll come up with it?
Stephen QUAKE: Well, in this case the impetus was becoming a parent. You know, I think like everyone that becomes a parent, one can only marvel at how amazing it is to create a new life and watch it grow, but before your baby’s born it also can be a very nerve- wracking time.
DUBNER: That’s Stephen Quake, a professor of bioengineering at Stanford. He’s developed a new prenatal test, inspired by his own impending parenthood.
QUAKE: And in my case, because my wife was over thirty-five and only had her first kid, the doctors recommended amniocentesis as a form of prenatal testing to look for Downs syndrome and things like that. And there’s some risk associated with the test because a large needle goes into mom’s belly, right up next to the baby to grab a few cells and to pull them out. And both sort of going through the procedure and the kind of the fretting while one waits for the results made a big impression on me. And we went through this whole thing twice, with two kids, and so that got me interested in perhaps trying to think of ways to develop non-invasive prenatal diagnostic tests.
DUBNER: Now, just walk me through your thinking on this. You were thinking you know what the procedure of an amnio is; it’s taking a big needle, it’s putting it into the mom, getting in to the amniotic fluid very close to the baby, right? So there’s some risk there, but then the reward is some early notification of potentially, you know, abnormal circumstances. How did you, as a scientist, and as a father-to-be go about thinking about the tradeoff between the risk and reward there?
QUAKE: Yeah, you know, it’s a really difficult question. And the way the doctors explained it to you they say that the risk of there being something wrong is about one percent. In other words that you’ll learn something from the test, that there’s a genetic abnormality in the baby, that’s about a one percent chance. And the risk of losing the baby because of the test is also about one percent.
DUBNER: That risk – of losing the baby as a result of amniocentesis – made a big impression on Quake. He thought: there’s got to be another way. So he got to work on a simple blood test. It turns out that when a woman is pregnant, DNA from the fetus is floating in her bloodstream.
QUAKE: And so each molecule was voting for a chromosome, and we’re essentially looking for voter fraud, for slight overrepresentation of one chromosome relative to another. And so if the baby has Down syndrome, there’ll be slightly more chromosome twenty-one molecules in the mother’s blood than any other chromosome.
DUBNER: Very good. So, what you’re talking about in a nutshell is, instead of amniocentesis, which is an invasive, and risky, and expensive procedure, relatively expensive procedure, you’re talking about a simple blood test to determine pretty much exactly what amniocentesis currently discovers, is that about right?
QUAKE: That’s about right.
DUBNER: Okay. So, if there’s a test, a blood test that’s non-invasive, not dangerous, presumably just about anybody who would be giving birth to a baby with Down Syndrome could or would find out about it in time to do something about it. When we say do something about it, that’s really a euphemism for abort. Talk to me a little bit about that framework, and what your test contributes to change that framework.
QUAKE: Sure. Well, let’s take your euphemism for a moment, because I’ll take issue with that. You know, it’s a very personal and challenging question about whether to keep or terminate a pregnancy with Down Syndrome. And there have been studies that have shown that for people who decide to take a Downs baby to term and deliver the baby, the earlier they know the baby has Down Syndrome, the more prepared they are to deal with it, and sort of the lower the stress, and the better the outcomes both for the kid and the parents. And so, my argument would be this sort of test adds value whichever side of the debate you’re on, whether you’re going to keep the baby or terminate it. The earlier you know the better, and it’s better for everyone.
DUBNER: And there are a lot of people who would argue that there is absolutely no reason in the world to terminate a Down Syndrome pregnancy, that there’s a strong population of Downs syndrome advocates, parents and people with it who say ‘Yes, this is a syndrome, it’s a set of challenges, a set of barriers, but not cause for termination.’ Do you have a position on that?
QUAKE: Yes, I do. And again, it’s sort of a very personal one, because it turns out that one of my wife’s cousins has Down Syndrome, and I’ve known him for nearly twenty years from the time I think I first met him he was four years old, and so, you know, kids with Down Syndrome, are very interesting, they’re warm, and open, and loving, and I can completely understand and sympathize with the argument to having a baby with Down Syndrome and deciding not to terminate having seen this kid grow up and what a wonderful kid he is.
DUBNER: Can you just blue sky and imagine what some of the surprising or counterintuitive consequences might be of having such an easier availability of a blood test that can detect Down Syndrome? Do you think there will rise up to be part of the population that says, you know what they easier it is then the more likely I am to not want to have it, because I want what life, and fate, and order, and God are going to give me? I don’t know. I’m just wondering what you thought through on that dimension?
QUAKE: Yeah, you know, it’s…The overall goal here I think is to lower stress. You know, impending parenthood is a very stressful time.
DUBNER: And you don’t need to add a big needle to it.
QUAKE: And that was kind of my motivation here. And so the hope is to make these tools available to people who want them and to lower their stress. And for people who don’t want them, it’s fine, it’s not something I’m going to impose on a larger world. That being said, you know, if you want to think about blue sky things, you know, we’re not very far away from being able to sequence the better part of the fetal genome non-invasively. And so you could learn many, many other things very early in pregnancy. And the question there is do you want to turn that lose on the parents?And…
DUBNER: And on society, really, right?
QUAKE: And on society, exactly. And the answer is I don’t know.It’s just… It would be horrible to think that people are going to take some sort of action because, you know, their baby’s eyes weren’t going to be the color they wanted, or they’re not going to be as tall as they wanted. These are things that you could presumably figure out pretty early on. And in practice I think it is a sort of self-correcting phenomenon. You know, it is challenging enough to conceive, especially these days, that people I’m hoping will not want to end it for trivial reasons. That’s where I hope it’s all going to equilibrate.
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DUBNER: Quake’s blood test, and another one like it, should be available quite soon. Now, how will parents respond? It’s hard to say: the future is the future – and as we’ve argued here in the past, the future is hard to predict. But don’t be surprised if we turn out to be... surprised. There are a lot of powerful laws in the universe -- but the law of unintended consequences may be one of the most powerful, especially when it’s applied to something as intricate, as intimate, as important as ushering a small new life into this big old world.