Technology and Birth Rates:

My post expressing skepticism about birth rate forecasts for 45 or 100 years in the future led me to think: What changes might substantially increase birth rates in the developed world?

Here's my candidate: A combination of (1) cheaper, less painful, and more reliable egg extraction and freezing, which would let 20-year-old women routinely bank eggs for the future, and (2) the invention of incubators that can safely grow a child from a fertilized egg to a live baby. It's of course impossible to be sure that development 2 will happen within the next 45 years, but I suspect that it will. Let's say for our purposes that it does. Why is this likely to substantially increase birth rates?

It seems to me that many couples have fewer children than they'd like, for several reasons. First, both the increase in women's educational and professional opportunities and changing sexual mores have led many women to marry later, and to have children later. They may still want to have 2, 3, or more children, but it becomes harder to do if you start in your mid-30s.

Second, pregnancy is hard work, especially if you also have one or two kids running around and contributing to your tiredness. Pregnancy and childbirth can also cause various health problems. Some women apparently really enjoy pregnancy and even childbirth, but I suspect that most don't. I doubt that this deters many would-be first-time mothers -- but it may deter some women who already have two kids, have experienced the unpleasantness of pregnancy, are older and thus more likely to find physical burdens more taxing, and feel less of a need to have that extra kid.

Third, I suspect that quite a few families might want to have another kid as their first batch gets older. Today, it's just not an option, at least without a great deal of work. (Adopting is of course always possible, but many people are reluctant to do that.) But if it becomes easy, I suspect a significant number of older couples may take advantage of it. Here I'm less certain, and of course as someone with two small kids I fully understand that many older couples may have no interest in going through all that again. Yet if even a substantial minority (say, 10%) do take advantage of new technology to do this, the birth rate may go up nontrivially.

So if age-related fertility decline stops being a problem, and the physical burden of pregnancy and childbirth is eliminated, two important deterrents to having more children would be eliminated. Naturally, there are plenty of other deterrents; technology won't make having children cost-free. But it will reduce the costs (I speak here mostly of nonfinancial costs) and thus increase the demand.

This is all guesswork on my part, and it may be skewed by the circles in which I travel. It would be interesting to see if there have been surveys that try to measure (however imperfectly) the extent to which people would have more children if the problems I describe were solved. Still, my suspicion is that this could easily drive up the birth rate by 0.2 or 0.3 per couple, or perhaps even more.

I have enabled comments.

Related Posts (on one page):

  1. The Sort of Thing That Drives Economists Up a Wall:
  2. Technology and Birth Rates:
Jonathan M (mail) (www):
I cannot help but think that you are treating people like a commodity (reduce costs and increase demand).

I think a big barrier to childbirth is actually our culture, which cannot see why investing into another is more important than investing in one's self.

Just a thought.
6.17.2005 4:18pm
qetzal (mail):
An increase of 0.2-0.3/couple in 45 yrs seems pretty aggressive. That requires about one couple in four to have one extra child using this technology. For that to happen, the technology has to be developed and become widely available and reasonably inexpensive.

Once that all happens, I think you're right that it could substantially increase birthrates. But I'm skeptical it will happen within 45 yrs. 100 seems more likely.
6.17.2005 4:24pm
Bill Harshaw (mail) (www):
I disagree. My understanding of history is an increase in life expectancy causes parents to reduce the number of children and increase their investment in each child. The changes operate within a framework of social norms, etc. So an increase in birth rates is likely only if mores change (i.e., more U.S. families become less achievement oriented and more family oriented (perhaps due to the rising proportion of Hispanics)); the cost of rearing a child goes down (i.e., college costs go down because professors take a 50 percent wage cut or higher education comes to be seen as a frill and not profitable); or life expectancy goes down (i.e., a catastrophe as described in Judge Posner's recent book). In the absence of such changes, I doubt that mechanical changes such as you postulate would have a discernible effect. Is there evidence that in vitro fertilization has had an effect?
6.17.2005 4:28pm
Mahan Atma (mail):
Just a note on your first post:

I had a career as a demographer before going into law, and I did a great deal of forecasting of fertility rates (as well as mortality and other demographic variables).

You say it's a mistake to forecast 45-100 years into the future, and I agree that it's highly problematic. But the problem is we're forced to do it anyway.

For example, the Social Security Trustees and their actuaries are tasked with trying to determine what is required to keep the Trust Fund solvent. They have to make some kind of educated guesses about what will happen over the course of our lifetimes. I'm not sure what you would have them do: Are they simply to give up and leave everything to chance?

By way of analogy, it's also difficult to forecast hurricanes well in advance of landfall -- but we have to do it anyway.

If you accept the idea that forecasting is a necessary if flawed science, the issue then is how to deal with the inherent uncertainty in our forecasts. In response to this problem, the cutting edge researchers in this field have developed something called "stochastic forecasting".

The idea is that instead of trying to estimate a single trajectory of future growth, you model the historical fluctuations with time-series models, and build the fluctuations into your future forecasts. You run a computer simulation where you simulate trajectories of future rates many times over. You let the computer generate the fluctuations randomly, with the same degree of variance observed in historical rates. Thus the simulated future trajectories bounce around in much the same way fertility rates bounced around in the past.

The result is a probability distribution of trajectories, so that we can say "We're 95% confident that the total fertility rate will end up between 2.8 and 0.5 by 2050" or somesuch.

Here are some sources, if you're interested in this stuff:


Lee and Tuljapurkar
6.17.2005 4:31pm
Stephen W. Stanton (mail) (www):
Seems like a bigger factor is the productive lifespan. Specifially, the big constraint seems to be the number of years a potential parent has to raise kids.

If you assume that parenting takes a fair amount of active involvement for 18 years, and you further assume the gap between the oldest and youngest child is 10 years, that's a 28 year chunk of time spent as an active parent. If you start popping out kids at 30, then you're not done actively parenting minors until 58.

Today, 58 is not considered "old" for most desk jobs. However, 58 is starting to hit the upper limit of most people's ability and willingness to deal with teenagers full-time.

Fact is, you can't get rid of the tradeoff between career success and involved parenting. You can minimize it, but it will always be there. Careerists give up much to have kids. Women like my wife wait until their 30's so they can cut back hours after hitting a high career plateau. Then they can negotiate great flex-time arrangements without giving up too much income. It takes almost a decade to hit that career "prime", between experience and grad school.

If you could extend the average person's career "prime" for another 20 years (say from 30 to 80 instead of 30 to 60) then scaling back the work schedule for 28 years becomes more of a temporary decision instead of a permanent one. People would keep having kids for 10 years instead of trying to have 2 right away.

Just my 2 cents.
6.17.2005 4:37pm
SW (mail):
Another technological change that might have the same effect is improvement in in-vitro fertilization that raises success rates or significantly lowers cost. That would affect young couples, who have plenty of time to have kids, but not enough money to try IVF ten times, as well as older ones.

Changes in the work environment may also allow people to have more kids. Telecommuting and flex schedules have made it easier to care for kids--similar developments would continue that trend.
6.17.2005 4:44pm
Dave Justus (mail) (www):
I think that declining birthrates in industrialized nations are more a reflection of a greater focus on individuality and self-sufficiency as opposed to a more family oriented world view than they are about technological advancements or the costs of children.

Volokh's technologies would enable people to have children later in life, and with less pain and time off from work, but this influence might end up being a net negative, rather than a positive in relation to birth rates. If you CAN reliably have children later in life, there is less incentive to have children early. So it seems likely that more people would choose this option. As time goes on, and they become more set in their ways, and more focused on their own personal lives (natural, since they have nothing competing to focus upon) it seems likely that many, who intended to have kids 'someday' never will.

It is a well known aphorism that New Yorkers never visit the Statue of Liberty. I think it plausible that a similar dynamic would form around child-rearing when people know that they always CAN, but never DO.
6.17.2005 4:47pm
Michelle Dulak Thomson (mail):
Dave Justus, that's exactly right. If your initial inclination is to put something off, you'll as likely as not put it off until it's honestly impracticable. At which point you say "Dammit," and then go on as you were.
6.17.2005 4:59pm
Bruce Hayden (mail):
A lot of good points above, and thanks for opening this up.

Parenting in your 50s is clearly different than in your 20's, or, heaven forbid, your teens. I will be, coincidently, 58 when my daughter graduates from high school in four years. She was my 40th birthday present.

Interestingly, she attends an expensive private school, and there and some of the kids have even older fathers there. The (often trophy) mothers tend to be a decade or so younger. In any case, the average age is probably late 40s for the fathers, late 30s for the mothers for these 14 year olds. There are practically no young parents there.

What I do find though is that, as a group, they are a lot more serious and thoughtful about their child rearing. Rarely do they scream at the kids when they aggrevate them, etc. I have been pleasantly surprised at how well these other kids are being raised.

I attribute this primarily to the fact that for many of us, I suspect, child rearing was very carefully thought out. You read a bunch of books on the subject at each stage, etc.

Obviously, my sample is highly self selected. But I cringe when I see how many of those who have their kids early in life handle them. No real thought about the effects their actions have on their children and their behavior.

So, I am all in favor of having kids later in life. I think in many cases, the parents do a lot better job of parenting than they would have, say 20 years, earlier in life.
6.17.2005 5:18pm
I'm inclined towards the opinion that the decrease of birthrates in developed countries stems from changes in general cultural attitudes and economic incentives. On the cultural side, I think that its telling that the birth rate in the US is near or at replacement, but if you look regionally, in the traditionally red states its above replacement and in urban/blue ares its below.

On a side, I would agree with Dave Justus that reproductive technology such as that described in the post would simply shift incentives to a later time frame, rather than amplify them.

Since parents no longer treat children as an economic safeguard in their old age, they no longer have motives to adequately hedge against retirement with large families.

In that vein, an alternative might be that the social security taxes from the child's generation would go solely, or mostly, to their parents for retirment. This would provide huge incentives for parents to place an emphasis not only having children, but also successfully rearing them.
6.17.2005 5:24pm
Bruce Hayden (mail):
I frankly don't see much in the way of having incubators in the near future. Technology shouldn't be that difficult. I suspect that we won't see it first here in the U.S. simply because of the ethical issues - the question of whether or not spending those nine months in an incubator loses kids some of what we define as humanity, as compared to being gestated, as we all were (so far) in utero. So, probably have to wait for the South Koreans, or some other similar country, tries it out first.

The other factor though that Eugene did not really address that ties in here is longevity. A decade or so ago, my best friend, with a degree in biology explained to me why we couldn't live forever. Had to do primarily with the DNA that apparently gets snipped off with every cell division.

But we are making major strides in that area, as we are in many others that can ultimately end up with us, or more likely our children and grandchildren, living a long, long, time, and doing this in the peak of health.

Indeed, I don't see it being that long before we can start reversing some of the signs and symptoms of aging. And I suspect that we are slowly zeroing in on some of the real causes.

For example, why are stem cells omnipotent, while most others are not? What exactly happens to a cell to turn off its ability to become almost any other type of cell? In the past, we pretty much have assumed that once a cell has lost this ability, it is gone forever with that cell's descendants. But some recent research questions this, with some of its offspring becoming, if not omnipotent, at least multipotent. Obviously, this is only one factor in how we age, but is shown here as an example of what is going on right now in science.

So, let us assume for a minute that science can extend life substantially, and, in particular, active life. What are the ramifications of this, esp. vis a vis child rearing.

It was fine having 2.1 kids when life expectancy was 60. Now it is somewhere around 78 or so in this country. (Not sure of the specifics, sorry, just making a point here). So, if you are going to live to 80, and start having your kids at 20, as do your kids, then there would be approximately 4 generations alive at any one time. And population would be roughly double that if we only lived to 40. But if life expectancy extends to 160, then we would have twice again as many people on this planet, as there would be eight generations alive at once, not just four.

Of course, this doesn't take into effect that some of us really like parenting. If aging were not an issue, some of us would not mind, and, indeed, would probably elect to continue to have kids almost indefinately. I know my girlfriend would - she is quite frustrated being a grandmother, and would much prefer being a mother again. I would too. Maybe one kid every ten years, alternating sexes (or genders, not quite sure which is politically correct right now).

The question arises then, what are the consequences of this. Potentially, we could end up with a lot of people exceeding the ZPG goal of 2.1 kids per couple, combined with the added number of generations live at once. This could, conceivably, have a serious impact on world population.
6.17.2005 5:43pm
Lou Wainwright (mail):
I suspect I travel in similar demographic circles to Eugene, as I found his assumption of increasing birth rates very plausable. My wife and I are continually shocked by how few of our friends have children, and even more surprised how few of them are going to have them. I'm 33, she's 30, and we are having our 3rd child in Oct. Of the 8 people in our wedding party, all in their low-30s, none have kids. Of our closest 10 friends each, only 3 (15%) have kids. About 30% are definately not planning on having kids, and another 30% are unsure. One of the reasons is that the woman are mostly professionals and when you only start thinking about having kids in your mid-30s you get bombarded with (seemingly accurate) risk factors about chances for birth defects, miscarriage, etc., resulting from pregnancy past 35.

Also, most of my male friends are engineers and half of them aren't even in a serious relationship even though they are between 32-38. Even if they want kids, they are going to have to get married soon, and start having kids immediately to avoid running up into the pregancy difficulties of the upper-30s.

One more factor, the rate of infertility problems continues to shock me. Half of the couples I've kmown (including my own) have run into moderate to serious infertility troubles. We are somewhat close to two couples in their mid-30s who have given up on kids because of too much stress from infertility (adoption is still being considered).

So to the extent that Eugene's technology improvements make it easier to have kids later in life (improved infertility treatments, less difficulties due to pregnancy) I think that birth rates among middle-class dual-earner families will increase. Now will that result in a significant contribution to worldwide population? I'm not sure.

Finally, I do worry that Dave Justus's point is right on. If you allow procrastination you may find more and more people putting it off until the 'right time' which never comes. But the babies that would be lost to that approach would be those that would otherwise have been born, "because this is our last chance to have a kid." That's only one child per couple who procrastinates. I suspect their would be a lot more 2-3 baby families among those who now can have kids later in life for a net increase in birth rate.
6.17.2005 5:44pm
Bruce Hayden (mail):

But one ramification of your suggestion is that it would reintroduce an incentive to have kids. Everyone would have to have one or two, just so they could get SS.

I read something years ago about the cause of the Baby Boom. Contrary to popular opinion, it apparently was not caused by all of a sudden having larger families, but rather, by a significantly larger percentage of the population getting married and having kids.

I look back to my grandparent's generation (born around the turn of the 20th Century). At least in my family, well entrenched in the U.S. by then, somewhere around half of them had kids. My parents both had a lot of maiden aunts and uncles as a result. Almost none in their generation though went childless, at least if they physically were able to. In my (relatively early) Baby Boom generation though, we went back to large number not having kids. In my family of five boys, I was the only one to have such. Even in my girlfriend's family, much more recently immigrated here, one of four did not.

My point though is that part of the ZPG that we have approximately reached is because of this phenomenum, and essentially conditioning government funded retirement on having children would reintroduce the incentive to have kids - at a time in our history when that may not be best.
6.17.2005 5:51pm
Bruce Hayden (mail):

Of course, some infertility may just be practice. My parents got married and started trying in late 1946. A year or so later, they started seeing a fertility specialist. Then, I came along in 1950, and any fertility problems were a thing of the past - five boys and three miscarriages in the next 13 years.

But I also think that you have a good point. For many, waiting too late is a problem. My ex probably couldn't have had another, even if she wanted to, and that was in her mid thirties.

The problem is worse because, while the women seem to realize that they are coming up against a fertility wall, as they enter their 30s, the guys don't. Many seem to figure that they have into their 40s to really settle down and start having their kids - so many seem to do that now. I have heard some blame this on female liberation, etc.
6.17.2005 5:58pm
Dick King:
"In that vein, an alternative might be that the social security taxes from the child's generation would go solely, or mostly, to their parents for retirment [if generations were lengthened to approximately half the span from birth to the midpoint of retirement]. This would provide huge incentives for parents to place an emphasis not only having children, but also successfully rearing them."

Not as individuals, because the free rider problem is immense even in a small nation. It doesn't incent people to invest more time and effort into their own children, although it might incent people to vote for policies that do just that.

6.17.2005 6:01pm
Bruce Hayden (mail):
Let me add to my previous post that I know a number of men who are still thinking of kids as they enter their 50s. Luckily for all concerned, they can't find willing, young, women to help out. I suspect that they will still be thinking this as they enter their 60s.
6.17.2005 6:04pm
Dick King:
I am more pessimistic than many about indefinitely increasing life span. I suspect that there are a number of instances of a resource that gets built up in infancy or youth and gets consumed at a constant but acceptable rate, or a substance that accumulates at a constant rate that there's no mechanism for disposing of. If the time to a severe problem averages 80 years there would be no selective pressure to solve the problem.

Teeth wear down. Eye lenses accumulate extra layers and stop focusing. Eye lenses also accumulate defects. No matter how long a woman lives and retains her youthful vigor she will run out of egg cells at some point and stop having babies. We have to find and eliminate all 437 of these to have a 250 year vigorous life span.

6.17.2005 6:10pm
Dan Simon (www):
An alternative hypothesis: the decline in fertility rates is self-correcting. Suppose that the desire to have children is a partially genetically determined trait. (It's likely influenced by culture, of course, but it's not unreasonable to hypothesize that something so crucial to reproduction is affected by genes.) Then, during periods where the incentives for childlessness are strong, the population will be heavily selected for the trait of irrationally desiring to have children. That is, children will be disproportionately born to parents whose genes give them a powerful urge to actually procreate (as opposed to, uh, merely "going through the motions", as it were).

This effect would be stronger, the stronger the disincentives--social or otherwise--to have children. And, conversely, when everyone is having children--during the "baby boom", for instance, as a previous commenter pointed out--this effect would all but disappear. I'm curious to know if there's any known empirical evidence for or against its existence.
6.17.2005 7:14pm
Renee (mail):
I don't think women will continue delaying childbirth like the Baby Boomers have. A lot of Gen X &younger women have chosen to start their families before their careers, and I think that trend will continue.

We may even see more of an age gap between husbands &wives as women in their twenties who are ready to start a family look for men already established in their careers and able to afford one. It's much easier to work with nature than to fight it.
6.17.2005 8:59pm
Dick King:
Taimyoboi, did I misunderstand you? I responded to what I perceived to be a suggestion by you that individuals are incented to have children and raise them well to improve their social security receipts when they retired, but other posters responded as if you had said that individuals' payouts are affected by their reproductive economic success. Are you suggesting that you don't get social security unless you have at least one child yourself and that child is successful?

How would that work? Clearly people who are in fact sterile should be exempted, or would you be required to take some level of fertility treatments before you give up? If so, that's a huge government intrusion. If not, how would you prove you tried and failed? And would men be forced to contract possibly bad marriages just to get their social security ticket punched? Gay men could buy ova and rent incubator time and raise the kids, I suppose. All and all, unappealing to my eye.

6.17.2005 9:14pm
Steve R:
My gut reaction is that the technologies Eugene posits would increase birthrates for developed countries. But probabally not by much due to the cultural costs weighing against having more than two or three children, not just the physiological costs of repeated gestation and birth. Keep in mind that one of the significant causes of high birth rates in developing (ok poor) nations and regions is the lack of birth control technologies.
6.17.2005 9:23pm
John Howard (www):
I think it is better if birthrates are increased by more people marrying and having children rather than by a few monster couples having lots of children. Those technologies wouldn't even necessarily be connected to couples in 30 years, the DNA will probably come from approved stock, and maybe the people that order up a batch of children will be a commune of evil union school teachers. Instead of measuring fertility rates by children per couple, we'll speak in terms of people per minute. Also, I don't like how taken for granted it is that the "developed world" is going to have children in a different way than the rest of the world. It perpetuates the exploitation that enabled this discrepancy to begin with. Why can't we even things out a little, and have our children younger and live a little less superficially during our twenties and thirties like other people do? (and you know, even if you are researching cancer or designing efficient cars or something, I still say that's the height of superficiality compared to having children.)
6.18.2005 4:23am
Brett P. Bellmore (mail):
Bruce has a point, about how older guys who'd like to have children have difficulty finding mates who are still young enough to be fertile. Which is where another technology comes in: International online matchmaking.

Imagine you're a well established guy in his 40-50s, divorced or never married, and you really want to have a family. Pre-internet, your chances in this culture of finding a woman who'd marry you, who's still of a fertile age, were essentially zero unless you were wealthy or famous. Your desire to have children was futile.

Today, in the same situation, you can go online at numerous sites, and "shop" among young women living in 2nd and third world countries, who are themselves looking for an older, established man to have a family with.

Relative to their situation, you ARE wealthy, and the technology makes finding each other easy. I'm already seeing a fair number of older guys married to young foreign looking women, and it's only going to increase in frequency.

Bet it's already effecting the birth rate here...
6.18.2005 8:51am
Jane Galt (mail) (www):
Bruce Hayden, that's not right; there was a large secular improvement in fertility worldwide from the 1940s to the 1960s. This paper argues pretty convincingly that it was due to all of the labour saving improvements in the mid-20th century, which lowered the "cost" of having kids enough to encourage more of them. In the end, it also raised the opportunity cost of women working, as it was now possible to take care of the house and feed the family part time; thus, the trend eventually reversed itself.

I don't find it convincing that an improvement in pregnancy technology would significantly raise the birthrate. Admittedly, I have never been pregnant; once I have been, perhaps I will find it more plausible. But most of the women I know, even second and third timers, aren't thinking about the difficulties of pregnancy. They are thinking about what having another baby will do to their careers, their wallets, or their sanity.
6.18.2005 10:34am
Goober (mail):
This seems like odd reasoning; it may be that getting a late start is the primary cause for decreasing American birth rates, but it strikes me as a peculiarly American phenomenon, not shared by those European developed nations that are also seeing decreased native fertility rates. Developed economies predominantly do experience lower fertility, but it's probably the result of social welfare making family welfare unnecessary in the twilight years, expensive cost of living (here in Manhattan two-child households are increasingly rare), and general societal attitudes towards large families.

Far more likely a contributor to increased American fertility is probably going to be an influx of immigrant populations with higher fertility rates. The Star Trekky explanation is fun, but probably not going to (1) affect that many women overall, nor (2) result in those women having substantially more children than they would otherwise. Indeed increased fertility techniques would likely only be used to have one more child. (Exception for fertility drugs that often result in twins and triplets.)
6.18.2005 6:46pm
Mike G. in San Diego (mail):
Hmmm. Do we really need to invent incubators (or "uterine replicators," as they are called in the novels of Lois McMaster Bujold)? The embryo (with its placenta) is essentially a parasite, and can grow in other places than a human womb -- and both deliberate experiments and accidents of nature (ectopic pregnancies) have shown that it isn't too fussy about where. Cross-species implantation has been successfully accomplished with livestock. For humans, you might want to specially engineer a transgenic animal for safety's sake ... but that might not be necessary. I wouldn't be unduly shocked if a human child were born within the next 15 years whose "birth mother" goes "Mooooo ..."
6.19.2005 5:37am
dave s. (mail):
Missing mostly from these posts is a big factor for us - housing costs. In my area (suburban DC) they have risen from about four times the yearly income of a beginning-teacher couple to about ten times in the last fifteen years. So if you have a sort of general notion that you ought to be established and able to provide for a kid, and if your inner image includes 'house with yard', you are going to postpone childrearing far later now than you might have fifteen years ago - and you get into the age-related loss of fecundity which people have been talking about.
6.19.2005 8:57am
"...a suggestion by you that individuals are incented to have children and raise them well to improve their social security receipts when they retired, but other posters responded as if you had said that individuals' payouts are affected by their reproductive economic success."

Well, it was intended entirely as a hypothetical, but a practical implementation of such a policy might in fact be a blending of the two. Tie a portion of the child's payroll taxes to the parents directly and the rest to a general pay-as-you go plan.
6.20.2005 1:13pm
Jim from Houston:
While Prof. Volokh's suggestion that "in vitro" pregancies would increase the birth rate is reasonable, but my personal experience in this area indicates technology that could keep teenage children "in vitro" would have a bigger market.
6.20.2005 4:19pm