Birth rate in the context of "Fertility rates"

Figures for the population of Europe vary according to the particular definition of Europe's boundaries. In 2018, Europe had a total population of over 751 million people. 448 million of them lived in the European Union and 110 million in European Russia; Russia is the most populous country in Europe.

Europe's population growth is low, and its median age high. Most of Europe is in a mode of sub-replacement fertility, which means that each new(-born) generation is less populous than the one before. Nonetheless, most West European countries still have growing populations, mainly due to immigration within Europe and from outside Europe and some due to increases in life expectancy and population momentum. Some current and past factors in European demography have included emigration, ethnic relations, economic immigration, a declining birth rate and an ageing population.

Earth has a human population of over 8.2 billion as of 2025, with an overall population density of 50 people per km (130 per sq. mile). Nearly 60% of the world's population lives in Asia, with more than 2.8 billion in the countries of India and China combined. The percentage shares of China, India and rest of South Asia of the world population have remained at similar levels for the last few thousand years of recorded history.

The world's population is predominantly urban and suburban, and there has been significant migration toward cities and urban centers. The urban population jumped from 29% in 1950 to 55.3% in 2018. Interpolating from the United Nations prediction that the world will be 51.3% urban by 2010, Ron Wimberley, Libby Morris and Gregory Fulkerson estimated 23 May 2007 would have been the first time the urban population was more populous than the rural population in history. India and China are the most populous countries, as the birth rate has consistently dropped in wealthy countries and until recently remained high in poorer countries. Tokyo is the largest urban agglomeration in the world.

Population momentum or demographic inertia is the tendency of the raw birth rate to rise as a result of past high fertility rates, even after fertility rates have fallen, or vice-versa. This occurs because a current increase in fertility rates causes an increase in the number of women of childbearing age roughly twenty-to-forty years later, meaning population growth figures tend to lag substantially behind fertility rates. Well-known examples include the Echo Boom (the increase in the total number of births as baby boomers reached child-rearing age) and Chinese population growth throughout the era of the one-child policy (from 1979 until 2021).

Population momentum explains why a population will continue to grow even if the fertility rate declines or continues to decline even if the fertility rate grows. Population momentum occurs because it is not only the number of children per woman that determine population growth, but also the number of women of reproductive age. Eventually, when the fertility rate reaches the replacement rate and the population size of women in the reproductive age bracket stabilizes, the population achieves equilibrium and population momentum comes to an end. Population momentum is defined as the ratio of the size of the population at that new equilibrium level to the size of the initial population.

Demographic transition is a phenomenon and theory in the social sciences (especially demography) referring to the historical shift from high to low rates of birth and death, as societies attain several attributes: more technology, education (especially for women), and economic development. The demographic transition has occurred in most of the world over the past two centuries, bringing the unprecedented population growth of the post-Malthusian period, and then reducing birth rates and population growth significantly in all regions of the world. The demographic transition strengthens the economic growth process through three changes: reduced dilution of capital and land stock; increased investment in human capital; and increased size of the labor force relative to the total population, along with a changed distribution of population age. Although this shift has occurred in many industrialized countries, the theory and model are often imprecise when applied to individual countries, because of specific social, political, and economic factors that affect particular populations.

Nevertheless, the existence of some type of demographic transition is widely accepted because of the well-established historical correlation between two factors: dropping fertility rates, and social and economic development. Scholars debate whether industrialization and higher incomes lead to lower population, or vice versa. Scholars also debate to what extent various proposed and sometimes interrelated factors are involved—factors such as higher per capita income, lower mortality, old-age security, and increased demand for human capital. Human capital gradually increased during the second stage of the Industrial Revolution, which coincided with the demographic transition. The increasing role of human capital in the production process led families to invest this capital in children, which may have been the beginning of the demographic transition.

Chile's 2017 census reported a population of 17,574,003 people. Its rate of population growth has been decreasing since 1990, due to a declining birth rate. By 2050 the population is expected to reach approximately 20.2 million people, at which point it is projected to either stagnate or begin declining. About 85% of the country's population lives in urban areas, with 40% living in Greater Santiago alone. The largest agglomerations according to the 2002 census are Greater Santiago with 5.6 million people, Greater Concepción with 861,000 and Greater Valparaíso with 824,000.

Demographic features of the population of Lithuania include population density, ethnicity, level of education, health, economic status, and religious affiliations.

The population of Lithuania increased after the end of World War II, reaching its apex in 1991 with 3.7 million, but started to decline after the Dissolution of the Soviet Union later that year, which negatively impacted the country. As social problems ensued after the dissolution of the Soviet Union, the birth rate decreased and the population fell sharply due to a relatively high death rate, mass emigration and a large increase of its suicide rate that made Lithuania one of the countries with the highest suicide rates in the world. This caused its population to drop below 3 million in 2012, losing over a quarter of its population in 30 years. As of today, Lithuania's fertility rate is one of the lowest in the world. However, while its suicide rate would remain the highest in the European Union, it dropped over time, and in the 2020's, the Lithuanian population would return to grow slightly due to immigration and a decreasing death rate.

Population ecology is a field of ecology that deals with the dynamics of species populations and how these populations interact with the environment, such as birth and death rates, and by immigration and emigration.

The discipline is important in conservation biology, especially in the development of population viability analysis which makes it possible to predict the long-term probability of a species persisting in a given patch of habitat. Although population ecology is a subfield of biology, it provides interesting problems for mathematicians and statisticians who work in population dynamics.

The population of the United Kingdom was estimated at 69.3 million in 2024. It is the 21st most populated country in the world and has a population density of 285 people per square kilometre (740 people/sq mi), with England having significantly greater density than Wales, Scotland, and Northern Ireland. Almost a third of the population lives in south east England, which is predominantly urban and suburban, with 9,089,736 people in the capital city, London, whose population density was 5,782 inhabitants per square kilometre (14,980/sq mi) in 2024.

The population of the UK has undergone demographic transition— from a typically pre-industrial population, with high birth and mortality rates and slow population growth, through a stage of falling mortality and faster rates of population growth, to a stage of low birth and mortality rates with, again, lower rates of growth. This growth through 'natural change' has been accompanied in the past three decades by growth through net immigration into the United Kingdom, which since 1999 has exceeded natural change.

The demographics of Nauru, an island country in the Pacific Ocean, are known through national censuses, which have been analysed by various statistical bureaus since the 1920s. The Nauru Bureau of Statistics have conducted this task since 1977—the first census since Nauru gained independence in 1968. The most recent census of Nauru was on 30 October 2021, when population had reached 11,680 people. The population density is 554 inhabitants per square kilometre (1,430 inhabitants/sq mi), and the overall life expectancy is 63.9 years. The population rose steadily from the 1960s until 2006 when the Government of Nauru repatriated thousands of Tuvaluan and I-Kiribati workers from the country. Since 1992, Nauru's birth rate has exceeded its death rate; the natural growth rate is positive. In terms of age structure, the population is dominated by the 15–59-year-old segment (57%). The median age of the population is 21.6, and the estimated gender ratio of the population is 101.8 males per 100 females.

Nauru is inhabited mostly by Nauruans (92.1%), while minorities include those from Kiribati (2.4%), Fiji (2.2%), Australia (1.2%) and other (2.1%). The demographic history of Nauru is marked by several migrations: the area was first inhabited by Micronesian people about 3,000 years ago. The first European to find the island was John Fearn in 1798. Then, the country was annexed by Germany in 1888. The next major population change was when Japanese occupied the island during World War II in 1942. During this time, the Japanese deported several thousands of Nauruans to other islands. In the 1960s, the country gained independence, where the percentage of Nauruans started to increase. The most recent demographic switch was in the 2000s, when the government repatriated several groups of non-Nauruans from the country.