Fertility Rates
Developed areas, like Europe, North America, and Australia, have more educated women and lower fertility rates. A higher percentage of women in the workforce leads to lower TFR, which leads to lower natural increase rates.
The Natural increase rate is the crude birth rate (amount of babies born per 1000 people in a year) minus the crude death rate (amount of people that die per 1000 people in a year).
In developing areas, like Sub-Saharan Africa, and South and Southeast Asia, women have fewer years of schooling and higher fertility rates. They also use subsistence farming, where more children can be advantageous to help farm. These reasons lead to higher natural increase rates.
There are many reasons as to why a country's fertility rate would change. A main large cause of a decrease in fertility rates is more education for women and easier access to family planning and reproductive health services (like contraceptives). There are also a lot of social causes, like a change in population demographics, or political instability.
There are a lot of cultural and social norms in developing countries that lead to larger family sizes, meaning that a larger family could be seen as economic security or higher social status. At the same time, more children mean more workers for the family farm, and generally, that is a family's income so they benefit by having more people working.
Mortality
Mortality varies in developed and developing countries. Developed areas have better hospitals, healthcare, and more access to birth control, which leads to lower infant mortality rates, which is the total number of deaths of children aged 0-1 in a year. Because of this children are more likely to grow to adulthood, which causes women to have fewer children.
Developing countries also have higher infant mortality rates, because of lack of healthcare and worse sanitary conditions. Birth control is less available. Because of this the TFR in some Sub-Saharan African countries is over 5!
Migration
Migration also varies in developed and developing countries. In the developed world, they have net-in migration, because people are coming to the country for better economic conditions.
The reason that the United States population continues to rise is because of net-in migration. The blue countries in this map represent places that have an increasing population due to migration. Most of these countries are developed, however, a few developing countries in Africa and Asia also experience a growing population due to migration.
In the developing world they have a net-out migration because people are leaving to seek better job opportunities internationally. Some also leave because the population of the country continues to rise, which can lead to overpopulation and overcrowding in urban areas.
Besides Natural Increase Rate, geographers also use doubling time, which is the number of years needed for a population to double, assuming the NIR stays constant.
However, NIR can change drastically for a number of reasons. War, famine, or political instability in a country can cause net-out migration to go up, or the TFR to drop. While those same factors in a bordering country can have the inverse effect.
Causes of Migration
Social
A social example is chain migration. That is when people move to a specific location because members or relatives of a similar nationality have already migrated there. This is very common as people typically try to move to places where they know other people and have an existing connection. It also leads to ethnic enclaves, like Chinatown. Ethnic enclaves are neighborhoods or communities within a larger region that are predominantly inhabited by a particular ethnic group.
Cultural
Cultural reasons people may migrate is because of their religion, beliefs, sexual orientation, or oppression of their ethnicity or race. This may be for forced or voluntary reasons.
People may choose to live in places that are religious centers like Israel, Mecca, or Salt Lake City (voluntarily). On the other hand, you could move somewhere for acceptance. For example, a person may want to move to somewhere more LGBTQ friendly.
Examples of forced migration due to culture are the Jewish diaspora, the Protestant Reformation, and the forced relocation of Native American tribes in the United States.
Political
There are two types of political migration. Voluntary migration is the permanent movement of people by choice. Forced migration is the permanent movement of people, who are compelled to move for different reasons. Sometimes the government is oppressing people, or they will move because of political instability or outright warfare. A lot of people are currently migrating out of Ukraine due to the current conflict existing there. This is a good example of forced migration.
Economic
Economics is the number one reason why people move to or within a country that provides more job opportunity.
This can be international, from one country to another, intra-national, within the same country, interregional, from one region of a country to another, or intraregional, within the same region of a country.
🎥 Watch: AP HUG - Decoding Population Pyramids
Frequently Asked Questions
What are the three main factors that cause population growth or decline?
The three main factors are fertility, mortality, and migration—exactly what the CED lists (EK IMP-2.A.1). - Fertility: how many babies are born (measured by crude birth rate and total fertility rate). Higher fertility raises population and lower fertility (below replacement ~2.1) causes decline. - Mortality: how many people die (crude death rate, life expectancy, infant mortality). Lower mortality (better health care, nutrition) increases population; spikes in mortality (epidemics, famine) cause declines. - Migration: people moving in or out (push–pull factors, international migration, refugees, remittances). Net in-migration grows population; net out-migration shrinks it. Geographers combine fertility and mortality into the rate of natural increase and use models like the Demographic Transition to explain trends (see Fiveable’s Topic 2.4 study guide for review) (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW). For extra practice, try the AP-style problems at Fiveable (https://library.fiveable.me/practice/ap-human-geography).
Why do some countries have really high birth rates while others have super low ones?
Short answer: birth rates vary because of differences in fertility, mortality, and migration driven by economic, social, cultural, and political factors. In more-developed places low birth rates come from higher female education and workforce participation, easy access to contraception and healthcare (low infant mortality), urbanization, higher costs of raising kids, and sometimes antinatalist policies—total fertility often falls at or below replacement (~2.1). In less-developed places high birth rates happen when infant mortality is high, children are economically useful, limited family-planning, traditional gender roles, and pronatalist cultural or religious norms. The Demographic Transition Model explains this: stage 2 countries have high birth but falling death rates; stage 4–5 have low birth rates. For AP prep, know CED keywords (TFR, crude birth rate, replacement-level fertility, pronatalist policy, DTM) and practice applying them (see the Topic 2.4 study guide: https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW). For extra practice problems go to https://library.fiveable.me/practice/ap-human-geography.
How do you calculate rate of natural increase and what does it actually mean?
Rate of natural increase (RNI) measures how fast a population grows from births and deaths only—it excludes migration. Formula options: - Using rates per 1,000: RNI (per 1,000) = Crude Birth Rate (CBR) − Crude Death Rate (CDR). - As a percent: RNI (%) = (CBR − CDR) / 10. Example: if CBR = 30/1,000 and CDR = 8/1,000, RNI = 22/1,000 = 2.2% per year. Positive RNI = natural growth; negative = natural decline. AP relevance: geographers use RNI (EK IMP-2.A.2) to explain population growth, compare stages of the Demographic Transition Model, and calculate doubling time (approximate doubling time ≈ 70 ÷ RNI%). For more practice and review on Topic 2.4, see the Fiveable study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and try practice questions (https://library.fiveable.me/practice/ap-human-geography).
What's population doubling time and how is it different from growth rate?
Population doubling time is how long it takes a population to double in size given its current growth rate. On the AP exam you’ll often see it linked to the rate of natural increase (RNI = crude birth rate − crude death rate). A quick way to estimate doubling time is the Rule of 70: Doubling time ≈ 70 ÷ (annual growth rate in %). So if RNI = 2% per year, doubling time ≈ 35 years. Growth rate (RNI) is an annual percentage—it’s the speed of change each year. Doubling time translates that speed into a time measure (years to double). Both are used in Topic 2.4 to explain population change (fertility, mortality, migration) and in DEMO transition discussions. For more review and practice on these formulas and examples, check the Topic 2.4 study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and thousands of practice problems (https://library.fiveable.me/practice/ap-human-geography).
I'm confused about how migration affects population - doesn't it just move people around?
Short answer: migration doesn’t just “move people around”—it changes who lives where, and that changes population size, growth rates, and structure. Migration (international or internal) adds or subtracts people from a place, so it directly alters population totals and can speed up or slow down growth even when fertility and mortality stay the same. It also reshapes age-sex pyramids and dependency ratios (e.g., young labor migrants lower a host area’s dependency ratio but can cause “brain drain” in the origin). Push–pull factors drive flows; remittances affect origin economies; refugee flows and policies affect political geography. For AP, link migration to the three demographic factors (fertility, mortality, migration) and use terms like rate of natural increase, age-sex pyramid, and carrying capacity (CED IMP-2.A). Review Topic 2.4 on Fiveable (study guide: https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and try practice questions (https://library.fiveable.me/practice/ap-human-geography) to see this on exam-style prompts.
What social and cultural factors make people have more or fewer babies?
Social and cultural factors that raise or lower fertility tie directly to total fertility rate, crude birth rate, and replacement-level fertility (about 2.1 children). Things that tend to increase births: strong pronatalist cultural or religious norms valuing large families, low female education and limited labor-force participation, high child mortality (parents have more kids as “insurance”), and traditions of early marriage. Things that lower births: higher female education and workforce participation, urbanization (higher cost of raising kids), widespread access to contraception and reproductive healthcare, rising age at first marriage/childbirth, and secularization or norms favoring smaller families. Government policies (pronatalist or antinatalist) and infant mortality link cultural choices to fertility outcomes. These are AP terms you should know for Topic 2.4 (see the Fiveable study guide: https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW). For more practice with these concepts, check Fiveable’s practice problems (https://library.fiveable.me/practice/ap-human-geography).
How do wars and diseases affect population growth in different ways?
Wars and diseases both raise mortality but affect population growth differently. Wars cause sudden, often age/sex-specific deaths (young adult males), lower fertility (disrupted families, economic insecurity), and produce large migration flows (refugees, displaced people). That can quickly reduce the rate of natural increase and reshape an age-sex pyramid (fewer working-age people), with long political and economic effects. Epidemics raise crude death rates and lower life expectancy too, but impacts depend on who is affected: a disease hitting infants raises infant mortality and lowers long-term population growth more than one mostly fatal to older adults. Diseases can also trigger policy or cultural shifts (healthcare investment, changes in fertility). Both are influenced by political and economic context (health systems, conflict control), which is exactly what IMP-2.A asks you to explain on the AP exam. Review this topic and practice applying mortality vs. fertility vs. migration effects in the Fiveable study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and try practice questions (https://library.fiveable.me/practice/ap-human-geography).
What's the difference between fertility rate and birth rate because I keep mixing them up?
Short answer: they’re related but not the same. - Birth rate (crude birth rate, CBR) = number of live births per 1,000 people in a year. It’s a quick, population-wide measure (e.g., 20 births/1,000 people). - Fertility rate (usually total fertility rate, TFR) = average number of children a woman would have over her lifetime at current age-specific fertility rates. It’s a measure of reproductive behavior and predicts long-term growth. Replacement-level fertility is about 2.1 children per woman. Why it matters for AP Human Geography: CBR helps calculate the rate of natural increase (births minus deaths per 1,000), while TFR tells you whether a population will grow, shrink, or stabilize over generations—key for questions on population change, DTM stages, and replacement-level fertility (CED keywords: Total fertility rate, Crude birth rate, Rate of natural increase). For review, see the topic study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and try practice problems (https://library.fiveable.me/practice/ap-human-geography).
Why do developed countries usually have lower population growth than developing countries?
Developed countries usually have lower population growth because of lower fertility and mortality rates driven by social, economic, and cultural changes. As countries develop (DTM stages 3–4), total fertility rate (TFR) falls—people have fewer children because of better female education and workforce participation, wider access to contraception, higher urbanization, and the higher cost of raising kids. Mortality (crude death rate) also falls earlier because of better healthcare and higher life expectancy, but lower birth rates eventually reduce the rate of natural increase. Lower infant mortality and replacement-level fertility (around 2.1) mean populations stabilize or grow slowly. Migration can matter locally, but birth and death rates are the main drivers (EK IMP-2.A.1, IMP-2.A.3). For more on this topic and AP-style practice, check the Topic 2.4 study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and extra practice problems (https://library.fiveable.me/practice/ap-human-geography).
How do government policies like China's one-child policy actually change population dynamics?
Policies like China’s one-child policy directly change fertility—the number of births—which shifts population dynamics through lower total fertility rate (TFR), lower crude birth rate, and slower rate of natural increase (IMP-2.A, EK IMP-2.A.1). Fewer births over decades produce an older age-sex pyramid, higher dependency ratios (more elderly per working adult), and potential labor-force shortages. It also caused a skewed sex ratio at birth in some areas (cultural son preference). Over time these effects force policy responses: relaxing limits, encouraging births, or changing immigration/migration strategies. On the AP exam, connect the policy to TFR, replacement-level fertility, population-doubling time, and changes in age structure (use EK keywords like dependency ratio and life expectancy). For a focused review on how fertility and policy interact, check the Topic 2.4 study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW). For more practice, try problems at (https://library.fiveable.me/practice/ap-human-geography).
Can someone explain how economic factors influence whether people decide to have kids?
Economic factors shape fertility (how many kids people have) a lot. Higher household income and urban jobs often lower total fertility rate (TFR) because kids are costly (education, housing) and women enter the labor force. In contrast, poorer rural economies may have higher TFRs where children add labor and there’s limited social security. National development changes this: as GDP per capita and female education rise, infant mortality falls and TFR typically drops toward replacement-level fertility (~2.1). Government economic policies matter too—generous pensions or pronatalist incentives can raise birth rates, while lack of childcare or high housing costs can depress them. For AP, link these effects to fertility, mortality, and the Demographic Transition Model (IMP-2 concepts). Want more detail or practice questions? Check the Topic 2.4 study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and the unit practice problems (https://library.fiveable.me/practice/ap-human-geography).
What are some examples of countries with declining populations and why is that happening?
Countries with declining populations: Japan, South Korea, Italy, Germany, Russia, and several Eastern European states (Bulgaria, Latvia, Hungary). Why it’s happening: low total fertility rates (well below replacement-level ~2.1), aging populations with higher life expectancy (raising the dependency ratio), and in some places higher mortality or net out-migration. These places are often in late stages of the Demographic Transition Model (stage 4 or 5), where births fall faster than deaths so the rate of natural increase turns negative. Cultural/economic factors—like greater female education and workforce participation, cost of childrearing, urbanization, and housing/childcare limits—lower fertility. Political factors (weak pronatalist policies) or sustained emigration can accelerate decline. For AP exam practice, you should be able to connect TFR, crude birth/death rates, dependency ratio, and push–pull migration in explanations (IMP-2.A). Review Topic 2.4 on Fiveable (study guide: https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and drill practice questions (https://library.fiveable.me/practice/ap-human-geography).
How do I write an essay comparing population growth patterns between developed and developing countries?
Start with a clear thesis: state whether developed and developing countries show higher or lower growth and why (fertility, mortality, migration). Organize body into 2 paragraphs (+ short conclusion): one listing similarities (both affected by migration, aging, policies) and one contrasting patterns using CED terms: developed = low crude birth rate, low crude death rate, low total fertility rate (~at or below replacement ~2.1), long life expectancy, aging/high dependency ratio (DTM stage 4–5); developing = high crude birth rate and total fertility rate, declining death rate (DTM stage 2–3), rapid rate of natural increase, young age-sex pyramids, higher infant mortality. Use examples and causes: female education, healthcare, economic development, pronatalist/antinatalist policies, epidemiological transition, push-pull migration. Quantify when you can and end with implications (carrying capacity, remittances, urbanization). For AP FRQs, “compare” needs similarities AND differences—don’t only list one side. Review Topic 2.4 study guide for facts and phrasing (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW), skim the Unit 2 overview (https://library.fiveable.me/ap-human-geography/unit-2) and practice FRQs at (https://library.fiveable.me/practice/ap-human-geography).
What causes some regions to have really high death rates while others don't?
Regions have high death rates (high crude death rate, high infant mortality, low life expectancy) for several interacting reasons tied to mortality in the CED. Major causes: weak health care and sanitation (so infectious disease and untreated conditions spread), malnutrition, poverty and low economic development, political instability or war that disrupts services, and older age structure (more elderly → more deaths). Environmental factors (drought, natural disasters) and cultural factors (low use of medical care) also raise mortality. As places move through the epidemiological/demographic transition, causes shift from infectious disease to chronic/degenerative diseases. For the AP exam, link these ideas to IMP-2.A and IMP-2.C (explain mortality, life expectancy, infant mortality). For a focused review, see the Topic 2.4 study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and try practice questions (https://library.fiveable.me/practice/ap-human-geography).
I don't understand why people migrate for economic reasons - can someone break this down simply?
People migrate for economic reasons mainly because of push-pull factors: push = lack of jobs, low wages, or poor living standards at home; pull = better employment, higher wages, and more services elsewhere. Economically driven migrants move internally (rural → urban) or internationally to find work, join labor markets (guest-worker programs), or access education that boosts future earnings. Remittances—money sent home—are a big part of the economic incentive: they can support families, pay for schooling, or fund businesses, which reinforces chain migration. On the AP exam, expect questions linking migration to economic factors, dependency ratios, and population change (Topic 2.4). For a focused review, check the Population Dynamics study guide (https://library.fiveable.me/ap-human-geography/unit-2/population-dynamics/study-guide/0TYTk8Xr7mXEcreDUVLW) and practice migration problems at Fiveable (https://library.fiveable.me/practice/ap-human-geography).