PRB Discuss Online: World Population, 7 Billion on the Horizon

(September 2009) On Aug. 12, 2009, PRB released the 2009 World Population Data Sheet at a press briefing in Washington, D.C. On Sept. 3, Carl Haub, PRB senior demographer; James Gribble, vice president for International Programs at PRB; Linda Jacobsen, vice president for Domestic Programs at PRB; and Mary Kent, senior demographic editor and co-author of the 2009 World Population Data sheet, answered participants’ questions during a PRB Discuss Online about world population growth.

Sept. 3, 2009 10:30 AM EST

Transcript of Questions and Answers

Geoffrey Gilbert: New research suggests that fertility has reversed course in some developed countries. Is anything similar happening in the developing countries, and if so, should we be worried?
Carl Haub: Fertility in the low birth rate developed countries does appear to have “bottomed out” and is rising again in some but remains at low or very low levels. Thus far, there have been a few cases of modest increases in the former USSR “Stans” countries but, generally, no one expects any large increase. It could ultimately happen when some of those countries also decline to very low levels.

rakesh chandra: is it still relevant to talk about population growth given the fact that problem lies more in resource allocation than population growth ?
Carl Haub: Your point is well taken except we do have to keep in mind that there remains a large amount of population growth in many countries. Sub-Saharan Africa will certainly add more than a billion before growth stops and even India could reach two billion despite having a moderately low birth rate. So, numbers are still an issue.

Diego Iturralde: Whilst most of the developed world is faced with declining fertility rates below replacement which poses certain challenges. In sub saharan africa there seems to be a thinking that tries to maintain fertility above replacement in order for there to be sufficient workforce, to care for the aged amongst many reasons. What challenges does this present in light of the world population reaching 7 billion and what is the future for Africa if such fertility trends prevail?
Carl Haub: I think the last concern Africa has is an insufficient labor force but rather too many untrained people entering the labor force year. In most countries, Africa would seem to already have enough people to develop if economic opportunities were there. But the lack of investment and widespread corruption would seem to preclude that.

JA Gavinha: Dear PRB, Some of the figures provided seem a bit difficult to understand, given the data provided. For instance, despite much higher rates of natural increase than the US, the population of Brazil is expected to increase by only 12% over the period 2009-2050, versus 43% in the US. Are there other variables considered, such as long term changes affecting natural increase and migration? Don’t you think the weight given to migration, especially in these changing economic conditions, is exagerated? How it is expected such a decline of population in Spain, considering its positive natural increase and the very high rate of in-migration? Thank you.
Carl Haub: The difference between the U.S. and Brazil is primarily due to migration. Will migration to the U.S. continue? In the long run, I would think it definitely would as the “pull” factor of higher incomes in the U.S. will always be there. The projection for Spain assumes little long-term migration and, with a total fertility rate below 1.5, Spain will not have positive natural increase for much longer.

James Gribble: According to the 2009 World Population Data Sheet, HIV prevalence has decreased from 5.7% in 2007 to 5.0% in 2007/2008. Prevalence figures represent the percentage of the population that is estimated to be infected with HIV at a specific point in time—it is not the same as incidence, which is the number of new cases estimated during a specific time interval. The decline in prevalence could be due to several factors. Many of the older estimates of HIV prevalence in African countries have been recognized as being too high and the historic estimates were never recalculated, which means that the baseline figures are artificially high. Also, without access to treatment, people living with HIV/AIDS may have died and are no longer in the population, which means that they do not contribute to either the numberator (people infected with HIV) nor the denominator (the total number of people, in this case, between ages 15 and 49). Another factor contributing is that prevention programs are having the desired effect and fewer new cases of HIV are occurring; although these cases contribute to the prevalence, if the number of new cases is fewer than deaths, then prevalence will decrease. If you look at the data sheet, you will see that the estimated prevalence in many countries has gone down, but has also increased in some countries. For a more comprehensive view of what’s going on with HIV in sub-Saharan Africa, it would be useful to look at UNAID’s annual report.

Meskerem Bekele, Ethiopia: Yes HIV prevalence in Africa is going to be decline. I think this is because of giving more attention and gives awerness for our society. But in FP I don’t think. If i take myself as an example I didn’t give my ears or they didn’t speak loudly for me about FP for the last years. But one year ago and know I am I start thinking and worriwd about our population density and I started to discussed from my friends about FP. I have tried to use this issue as a programe.- So do you think that we African’s did about FP effectively? – who is going to be an action taker about FP issue? government? NGO? or each families? we know that using contraseptive is one of the tools for FP. But many womens complained about the side effect of these contraceptive methods. Yes I know all good things also have its owen side effect but do you think that one kind of contraceptive method is suitable for the other women? do you think that health professionals advising these women?

Thank you for your information about world population data sheet and the others.They gave me too much input for our radio program.
James Gribble: Thanks for your questions…they raise some important issues about getting information to policymakers, media, and the general public about the importance of family planning. It is interesting that what got your attention was thinking about population density, and perhaps the link between population growth, the environment, and food security—and they are all interrelated. And it is great to hear that through your interest, you are becoming a champion for family planning, which is linked to economic growth, better health, and better opportunities for the future. There has been a lot of attention put on family planning in many African countries. Many donors are putting more and more attention on increasing political commitment, funding, and access to services in African countries. In Ethiopia, work with community health workers is increasing access to services, and we can see that it makes a difference—prevalence has gone up tremendously in the past few years. But there is no magical combination to make family planning programs work. It does require political commitment, as has been seen in Rwanda in recent years; it takes services and commodities, which requires funds; it takes communications efforts to get positive messages out about benefits of smaller families, the health benefits of birth spacing, and the economic benefits of slower population growth. I think it requires a concerted effort with each sector playing a part: government, NGOs, community members, the commercial sector, media. Regarding side effects of family planning methods—there are many different types of methods—hormonal, barrier, fertility awareness, permanent. Some women are better suited for certain methods, which is why good counseling and follow up are important. If a woman has problems with a certain method, she should return to her provider so that she can get a different method that responds better to her body and lifestyle. Women and couples should be able to decide on the timing and spacing of pregnancies and birth. Family planning programs are designed to help achieve this important goal. As you can tell, this is something that I could write on and on about. I hope that you will go to the PRB web site and take a look at some of the publications we have put out in recent years that focus on why family planning makes sense for better health and wellbeing (

Adhikar Dhakal: Will there be a law or a rule enforcing how many children a couple can bear?
James Gribble: Now that is a straightforward question! And I think it has a straightforward answer—no. Who would promulgate such a law? How would it be enforcable? And who would support it? The decision to have children is very personal and should be respected. Historically, large families were important for economic and social security reasons. Although the world has changed, people have different reasons for having the number of children they have. But many women end up having more children than they want, and many women do not want to get pregnant, but do are not using an effective contraceptive method. Perhaps a better alternative to a law or rule is to increase access to and knowledge about family planning, work to empower women so that they have more say in decisions about family size, work with men to be more constructively involved in fertilty decisions, and work with policymakers to enact policies that support well designed and implemented programs in health, education, and economic growth. I think that the solution is not is a heavy-handed law, but rather in empowering people with the tools, skills, and services they need to decide for themselves.

Tope Akintunde: a.)What are the factors responsible for the rapid population growth all the over the world? b.)Despite the awareness and the use of contraceptives in the developed countries especially US, what do you think is affecting the increase in the teenage pregnancy and birth in the US?
Linda Jacobsen: a.) Rapid population growth in less developed countries is due to high birth rates and a young age structure. In more developed countries experiencing population growth, immigration plays an important role. In the U.S., replacement level fertility and immigration both contribute to population growth .b.) Part of the increase in the teen birth rate in the U.S. is due to an increase in the share of teens from high fertility subgroups such as Hispanics and immigrants from high-fertility countries. Some data also indicate the teen birth rate is up due to a slight increase in sexual activity, a decrease in the use of contraception, and continued decline in abortion rates.

Nir, F.: what is your definition of poverty?
Mary Mederios Kent: Because poverty may represent different things in different countries and the values of international currencies vary, it is difficult to come up with a measure that is comparable internationally. The World Bank uses several measures of poverty, including the distribution of income within countries, which is just as telling as the national average. The World Bank measure we used on PRB’s 2009 World Population Data Sheet is based on the percentage of a country’s population that lives on less than US $2 a day—calculated as purchasing power parity (PPP). PPP is the amount of a country’s currency required to buy the same amount of goods and services in a country’s domestic market as a U.S. dollar would in the United States. The World Bank also estimates the percentage of a country’s population living on less than US $1.25/day.These estimates are based on surveys and other information about consumption and income gathered from each country. The poverty report can be found at See the World Bank’s World Development Indicators for more information.

Vijay Aryal: The world is trying the best for reducing the fertility and mortality rates in case of the developing countries whereas it has been a matter of concern to promote the level of fertility among the industrialised countries. In this context, how would the control of population growth be remarkable at this juncture of reaching at seven billion population?
Mary Mederios Kent: We are on track to reach 7 billion before the end of 2011, and will likely add another 2 billion by 2050. These projections assume fertility will continue (or start) to decline in developing countries with high fertility today. But couples in high-fertility countries need access to family planning services and information for fertility to decline further. There is currently a great unmet need for these services—an estimated 200 million women want to control the timing or number of their pregnancies but are not using an effective method of family planning. The developed countries with very low fertility may or may not increase their fertility levels in the next few decades, but this will not have a great impact on world growth.

M.S.Makki: It is a dilema position. The birth rate in developing countries still high due to traditional demographic behaviour, and also high in some developed countries due to exagerated freedom of teenagers. Do not you think it is time to think hard and work on strengthening religious moral and attitude to abondone false traditions and control birth to be only through marriage ties?
James Gribble: Thanks for an interesting question. To answer it, I’m going to step back to the proximate determinants of fertility framework, which indicates that fertility is a function of age at marriage, contraceptive use, sterility, abortion, and postpartum insusceptibility. In many developing countries, many young women are married at early ages and have limited access to family planning. These two demographic behaviors are driven to a large extent by culture—certainly early marriage is, and in many places, social pressures to start childbearing as soon as the young woman is married is also a cultural force to be addressed. Young women often lack access to family planning and are socially encouraged to have many children within marriage. Are these the types of false traditions that you are referring to that contibute to higher fertility among young women? In many of the places where young women marry at young ages and are encouraged to have many children, religion is also one of the dominant forces that shapes demographic behavior. I am not clear if your issue is early childbearing, which has a lot of adverse effect on health and future opportunities, or early fertility outside of marriage. Regardless, the risk factor for adverse health outcomes is the woman’s age. I am not an expert on adolescents, but the attempt to constrain some behaviors may have a counterproductive effect. Perhaps programs that focus on youth need to start at an age that helps shapes their attitudes and values so they make good choices. Some will become sexually active—that’s a fact of life; but when they have necessary information and access to services, they are better equipped to avoid adverse outcomes, such as unplanned pregnancy, HIV, and sexually transmitted infections.

charlie teller: Concerning continued rapid pop growth in in LDCs, the significantly lowering fertility [is] found mainly in the urban and educated classes, so that those disparities within countries are also … growing. Thus the youth bulge will be greatest in urban areas, where jobs for youth are scarce. Can you contrast the potential positive demographic “dividends” of this urban youth bulge (eg., more female education, later marriage, technological innovation, etc.), as well as the usual negative ones?
Mary Mederios Kent: You bring up some good points. Countries have an opportunity to benefit from a rapid and substantial decline in fertility—the “demographic dividend”—because there are more working-age people to support dependent-age people (the very young and very old). This may have helped South Korea’s rapid economic growth in previous decades. However, reaping this dividend requires a skilled, educated labor force and favorable political and economic conditions. Where there are not enough jobs for youth entering the labor force, educational levels are low, and the goverment is ineffective, there is no “dividend.” Often there is widespread unemployment and underemployment, and as you point out, this is often a greater problem in urban areas.

John Bermingham: Hi, Carl, Mary and others. If appropriate for thia discussion please explain that UN close in projections are like PRB’s but not for 2050 because… Also, that UN global high and low are very unlikely since they assume every nation follows its high projection every year for 40 years (or low for 40)and this is totally unlikely.
Carl Haub: Hi John, The projected 2050 population on the data sheet is necessarily different from the UN since we use a variety of sources (including some of our own projections) such as official national projections of countries where available. We don’t know where it’s going end up until we add it up! The data sheet’s 2050 population is 271 million higher than the UN but half of that difference is accounted fior by our higher projection for India. Of course, all countries are not all going to follow any variant of the UN but I think it’s practical to use a uniform assumption within each variant. That way, at least one readily knows what is being assumed. It’s also obviously possible to select countries from different variants and come up with your own total. One, might, for example feel that the medium variant is too optomistic for Africa, too pessimistic for some other countries, etc.

Craig: The trend between increased economic development and lower fertility is pretty well established. However, a recent study published in Nature showed at very high levels of the Human Development Index, fertility actually begins to increase again. Do you have any thoughts?
Carl Haub: Craig, I have to be frank and say that I did see that article and was a little puzzled why such a simplistic attempt to explain fertility trends was attempted. A country’s birth rate is the result of a complex group of influences, such as governments’ support of young families, the social acceptance of childbearing outside of formal marriage, the labor market, and so many more. Factors that influence fertility in different countries do have some commonality but also vast differences. One of the faster rates of fertility increase in Europe is in Russia which has a fairly low income level. That’s apparently due to the government’s recent offer of $9,000 for the birth of second and subsequent births.

Craig: What are your thoughts on future population projections as they relate to environmental sustainability and resource constraints? There has been increased violence and unrest surrounding growing food and water scarcity, especially in many African countries. How will these issues be affected by the projected population increases primarily in developing countries?
Carl Haub: While no one predicts such things, the pressure will certainly be there. What, for example, will happen when Uganda approaches 75 million or 100 million? People will have had to have moved to towns and cities seeking some form of income. I would imagine that could lead to considerable unrest.

Dave Plane: I have two questions that I’d be interested in the panelists thoughts about…1. What do you think the effects of the current global economic slowdown has had—and will have in the future – on world population growth? 2. The latest data sheet shows Mexico with a TFR of 2.3, the USA at 2.1. Will Mexican fertility follow the Spanish model and drop below that of the U.S.? If so, how soon until they are equal and how much below might it go? (Of course there will still be substantial population momentum due to young age structure.)
Mary Mederios Kent: First, the global economic recession is likely to have a temporary effect on both fertility and mortality that could slow population growth, especially in the poorest countries. But it is not likely to have a big long-term effect on world population growth. Concerning Mexico’s future fertility levels, I don’t see that it will necessarily follow Spain’s model and fall to very low levels. However, with Brazil’s fertility now the same or slightly below that of the US, it would not be surprising if Mexico’s TFR fell to 2 children per woman or below within the next decade. Of course, the US TFR may fall as well. The UN projects that Mexico’s TFR will be 1.85 by 2025.

Mike Blackmon: How long will it take for the world’s population to double?
Mary Mederios Kent: Current projections don’t show world population doubling. Long-range projections show a leveling of growth in the second half of this century. However, if the world’s current growth rate of 1.2 percent continued for at least 58 years, world population would double.

Carl Haub: Well, doubling would suggest that it would approach 14 billion at some point. As risky as it is, I’d predict that won’t happen but that growth may end at somewhere around 11 billion and possibly not until the next century.

Mahmoud: Why we do not concentrate on productivity specially agricultuer, to insure good nurtition?
Mary Mederios Kent: You might want to look at some of our publications on nutrition and to look at the work done by the International Food Policy Research Institute and other groups working on agricultural productivity issues (

C. Norwood: Since the turn of the 20th century population scientists have been sounding the alarm on population growth and its consequences for national economies, national security, the environment, and gender inequities and yet the world population steadily growths.

So, just what is an ideal world population size and why that number? Additionally, what is the goal – is it to stabilize population size?
Carl Haub: The question of ideal size comes up frequently and, of course, can never really be answered given the huge number of variables. However, Joel Coen did publish a book collecting many estimates of how many people the Earth might support and an average of all of those, as I recall, was around 11 or 12 billion.

Cletus Tindana: Thank you PRB for this opportunity. I would want to enquire on the reliability and accuracy of some of the data that is presented to the world from developing countries. The organisation in which I work runs a DSS (demographic surveillance system) and we tend to see more accurate and reliable data and when this is compared to other districts of similar population characteristics, ours most often tend to be different. e.g comparing fertility rates tend to be very different. What are the main sources of most of this data represented in most developing countries.
Carl Haub: The underlying sources are, of course, censuses but data availablity has improved greatly, beginning with the World Fertility Surveys. Today we have many surveys such as the Demographic and Health Surveys and many others that provide good estimates of a variety of demographic measures. Some developing countries do have good registration of births and deaths while India has a Sample Registration System that is likely much like your DSS.

Geoffrey Gilbert: Is there any way to identify the most important reasons why fertility has fallen so low in the industrialized countries? People mention various factors, but it seems they are mainly speculating.
Carl Haub: The reasons can vary a great deal by country but a fairly constant thread is economic: the actual state of the economy and the confidence couples have in it. The fact that buying or renting a house requires a full-time permanent job, not a temporary one (a problem in Italy). And there is an elusive, not easily measured, factor such as a change in young people’s expectations and tastes that simply makes starting a family far less automatic than it once was.

Mike Blackmon: In what ways have educational improvements for women aided this segment of the population in less developed countries, especially Afghanistan?
Mary Mederios Kent: Education for women has been linked with many benefits, for the individual woman, her family, and community. Research shows that women with more education are healthier and have healthier children, for example. They are more likely to use effective family planning and have the number of children they want. If women in Afghanistan are able to improve their educational levels, they and their families will reap these same benefits.

See the press briefing at the National Press Club, Washington, D.C., for the 2009 World Population Data Sheet, with Carl Haub, James Gribble, and Linda Jacobsen.

The 2009 World Population Data Sheet and companion report are available at