The GiveWell Blog

Infant mortality and overpopulation

When looking at programs that mostly target infant mortality, I’ve mostly thought of them as “population-increasing” programs. I’ve sympathized with donors who say that bigger populations might be the last thing poor villages need, and I’ve also assumed that “strict utilitarians” are likely to value such programs more than I do. It’s interesting to see the Report of the Commission on Macroeconomics and Health try to turn this issue on its head:

…high mortality rates of children tend to provoke high fertility rates among poor couples. In general, the high fertility more than compensates for the high mortality … In one numerical illustration, households whose children have a 75-percent survival rate choose to have six children, of whom an average of 4.5 survive. The households whose children have a 95-percent survival rate have two children, of whom an average of 1.9 survive … This pattern helps us to understand the surprising fact that countries with high infant mortality rates have the fastest growing populations in the world…

The report includes charts (see Pgs 35-38) showing a pretty strong association between low infant mortality and low population growth across the world’s nations.

This statistical association doesn’t necessarily mean the above logic is correct; it could be that something else, such as economic prosperity or education, is associated with both low infant mortality and low population growth, and that simply lowering infant mortality wouldn’t reduce fertility.

Not being aware of any studies on this specific relationship, I looked a little further using Gapminder. Rather than looking across the world’s countries (as the Report does), I looked specifically at countries within sub-Saharan Africa over time, which seems more relevant to the hypothesis that lowering infant mortality in high-mortality, high-fertility countries (such as those in sub-Saharan Africa) is associated with lowering fertility.

Since 1950, these countries have seen noticeable declines in both infant mortality and fertility (children per woman). However, the trends don’t sync up. In particular, since 1990, infant mortality has largely remained flat while fertility has continued to decline. (Note that literacy has improved over this time period as well.)

I’m hesitant to go as far as the report in calling infant mortality a primary, or the primary, driver of lower fertility. Still, it is clear at least that reducing infant mortality need not result in population growth. I don’t know of any more thorough studies on the link, and would be interested in any references.


  • Barbara Clarke on August 4, 2008 at 10:05 am said:

    The causal relationship between fertility rates and infant mortality was pretty well established about twenty years ago. There were many World Bank studies around that time.

    What you are probably finding in your current research is that once the infant mortality rates have dropped to a certain point, other factors such as education become more influential in reducing fertility rates.

  • Holden on August 4, 2008 at 7:17 pm said:

    I should have mentioned the other way in which the two trends don’t appear to sync up, which is that the drop in fertility seems to be concentrated after 1980 whereas the drop in infant mortality was pretty consistent from 1960-1990. This seems to further undermine the idea that the latter causes the former.

    That said, this was pretty cursory analysis and I’m very interested in the studies you mention; if you could direct us to some, I’d appreciate it.

  • I agree with Barbara that the relationship is well established and pretty much taken for granted. Being a qualitative researcher, I have very few skills in statistics (OK, I admit it, none at all.), so this question may be irrelevant: would it not be normal that it would take a significant chunk of time before the drop in fertility would become apparent?

    What I do know is that it can be difficult to show cause and effect. An infant mortality reducing program may have been implemented in an area with many other programs. So, while the former program’s baseline indicators may have changed for the better, it’s not often that you know for sure that no other factors were influencing the outcomes. In my experience, when areas/regions “open up” (as a result of improved security, accessibility or whatever) it does not take too long before several aid agencies are present.

  • Holden on August 5, 2008 at 10:53 pm said:

    Pia, I agree that it’s difficult to show causality for something like this.

    We are interested in this question, and will be sure to get a better grip on the academic literature that exists on it (though it isn’t currently our top priority).

  • Nathaniel on August 11, 2008 at 1:50 pm said:

    Lowering mortality may not lead to population growth. I understand the theory that as long as people understand their children will live they feel less compelled to have more.

    However, why the concern over population growth? If you look to environmental reasons I would put forth the argument that limiting population doesn’t limit things like pollution. China is an example of population control and intense pollution (surpassing the USA in CO2 emissions years after its started the “1-child” policy) occurring alongside each other.

  • Evasta on August 12, 2008 at 1:41 pm said:

    Why the concern over population growth?! Um, because it assures future cataclysmic suffering and death?

    We’ve already exceed global carrying capacity. We are now in “overshoot”. Global population is nearing 7 billion. Global carrying capacity is about 2 billion. (This assumes some level of social justice and a moderate, low by US standards, standard of living.)

    We will get to that 2 billion number the hard way (wars, famine, disease, and their accompanying losses of environmental quality, freedom, and social justice) OR the less hard way (immediately and drastically reducing our population voluntarily).

    It’s also far too late for any “us” vs “them” arguments or any belief that national boundaries will do much to help anyone. This is a global issue with local and nation-state consequences. Immigration is a consequence of overpopulation, not a cause of it.

    The benefits of “alternative” energy technologies will not ‘save’ us either, population growth overtakes those benefits rapidly, often within mere months.

    One of the key factors in this scenario is also our sense of time. This is a slow motion crash that requires immediate action, a bit like trying to steer a supertanker by putting in consistent input over a multi year time frame, and that input is stop making babies.

    (And it was oil that allowed us to get this far out on a limb, and peak oil has already happened.) For more on this I suggest

    One of his best is The Elephant In The Room, which does a good job of linking population with oil.

  • Nathaniel, I don’t fully get your argument re China. China’s population is currently 1.3 billion. If they had never introduced their “one child” policy, their population would be higher, say 1.6 billion. The question re pollution is are they are emitting more or less pollution than they would be if they had 300 million (or whatever the number is) extra people? There’s no way to run the experiment of course, but my high conviction guess is higher. Do you disagree?

    As an aside, China’s population is still growing. Demographers estimate it will peak in 2030 or so.

  • Nathaniel on August 12, 2008 at 7:00 pm said:

    Crust, I actually lean towards disagreeing-and most certainly questioning.

    I know that China is still growing but the birthrate has notably fallen. If the pollution emitted was due to population size then pollution emissions should have still risen but by smaller amounts than before. Instead the amount of emissions generated in China have been rising by greater amounts than before. This fact implies that something may be questionable about the assumed relationship between population size and pollution.

    A relating point is that measuring the size of a population does not measure those items, devices, and constructs that have a direct relationship to emissions. Thus measuring population size does not tell you how many cars are in use or how many coal power plants are in operation. Cars and coal power plants are only two types of things which directly emit pollution from the burning of fossil fuels but they also serve as examples of things that have been growing rapidly in number in China as the birthrate falls. As they are both sources of pollution we should be more concerned about a change in the number of each. And it makes a certain amount of sense to look for something that is changing or growing rapidly when looking for an explanation for the rapid rise in emissions from China. Thus the focus on population size missed the more legitimate targets of concern.

    I would argue that if China had those 300 million additional citizens but fewer direct sources of pollution (less automobiles, power plants, and factories) that it quite possible that the amount of Chinese emissions would be lower than it is today.

    In addition, my understanding is that if anything close to the current US lifestyles and consumption levels becomes worldwide then the world would face profound environmental harm. The US already should change its consumption habits because of the ecological damage being done. The more other nations mirror these habits the greater the problem. Also these consumption habits do not stay stable. What one thought of as an average US household once had only one car or television set-now it is common for there to be more of each. This trend of increasing consumption has not been slowed by smaller family sizes-again leading back to the point that limiting population size does not limit consumption, fossil fuel use, or related pollution.

    Consumption levels tend to be highest in those nations with lower birthrates as these also tend to be the most developed and wealthy nations. Thus low birthrates may even imply greater emissions and consumption. I’m not sure if I would call them a symptom or cause but the Solow model of economic growth does tend to view population size as a detraction from the amount of wealth that can be invested-thus limiting population may allow for greater economic growth. When discussing economic growth and investments in China they tend to be for things that encourage or cause greater pollution. New highway systems (which promote more automobile use), factories, and so on. And this is especially bad in China because there is little in the way of effective environmental regulation there.

    Oh, one point on alternative energy (which was a point Evasta raised). I once heard that enough solar energy hits the Earth in one hour to power the whole of current human civilization for a year. I freely admit there are large and complicated problems with trying to harness this or other alternative sources of power, but implying that there is not enough alternative energy strikes me as underestimating it.

  • Nathaniel, one way to look at the question is to break down total pollution into the product of GDP and pollution per unit GDP. The latter term (pollution intensity of GDP) would be roughly the same in either case (there are offsetting effects). But while per capita GDP would likely be a bit lower (and hence per capita pollution a bit lower), total GDP would surely be significantly higher (hence ditto for pollution). If you prefer to think of this in terms of proxies for pollution like the number of automobiles or the number of coal-fired power plants, I’d come to the same conclusion: Per capita numbers likely a little lower with higher population but aggregate numbers surely higher.

    It is true as you say that low birthrates are correlated with higher per capita emissions. But I think that the primary arrow of causality here goes from wealth to lower birthrates and higher emissions. In other words, the correlation is primarily a marker of a third variable, per capita GDP. To the extent that lower birthrates do cause higher per capita emissions, I suspect that’s normally not nearly enough of an effect to increase aggregate emissions.

  • Nathaniel on August 22, 2008 at 7:49 am said:

    Crust, I’m sorry I took a week to post again.

    The word “surely” implies you are assuming that a larger population means a larger economy. But it isn’t hard to find nations with both populations that are larger (or equal to) other nations and measurably smaller economies. Also you are assuming higher birthrates leads to only “slightly” lower GDP when it, or lower birthrates, could a be more significant factor than that-especially over time.

    Another example of the size of GDP not being determined by population size is evident when you compare France and the Democratic Republic of the Congo (which has been in the news for other reasons in recent years). France has around 64 billion people. The Democratic Republic of the Congo has more that 66 billion. Thus you would expect (if you base assumptions on population) that these 2 nations would have economies of similar size with that of the Democratic Republic of Congo being slightly larger. Yet France has an GDP of about 2 trillion dollars and the Democratic Republic of the Congo has a dramatically smaller GDP of almost 19 billion dollars. Even if you try to blame the a portion of the difference in the GDP of the two on a recent crisis you would probably be hard pressed to find a time when France’s economy equalled or was surpassed by that of the area that is currently known as the Democratic Republic of the Congo at in point in the last 500 years.

    Also the general fact that nations are frequently measured by per capita GDP should indicate that the size of a nation’s economy is not determined simply by its population (otherwise this particular variable would be similar across all nations and there would be no reason to compare one nation to another with it).

    GDP is a way to not only to measure what a nation produces but if that nation is a wealthy one or not. Thus the higher GDP per capita, being related to the higher size of GDP, can push the arrow of causality (in relation to emissions) back to wealth. This last point has some logic to it as an economy (or individuals) need to be able to afford either purchasing or the process of building many of those things that can be pointed to as direct sources of pollution. Thus there is likely to be a correlation between the size of an economy and the amount of emissions.

    There is no guarantee that the aggregate pollution would be higher in a nation with a larger population but a smaller economy. I would put forward the argument that a correlation between GDP and emissions is much more likely to be accurate than one of population size and emissions. In other words, I would expect a nation with a higher GDP (regardless of population size) to have more emissions rather than one with simply a higher population.

    One last side point, while I have mainly focused my argument for the size of the economy rather than that of the population being the cause of emissions I haven’t measured if pollution intensity of GDP is increasing or decreasing with GDP (if the increase in the size of GDP reflects investments that have higher emissions per unit of GDP or not). If it is then that would bode for even greater problems in the future.

  • Thats interesting that statistically mortality gives rise to fertility. What I am not following is do they think it is a mental thing where people overcompensate with the number of children to ensure some survive? I would imagine that modern birth control methods and other similar factors (such as having children to help with work such as farming) have a good impact on the results though which mat throw off the results by a dramatic margin.

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