DTM is the abbreviated form of the Demographic Transition Model. Scientists designed this model to better classify population trends over time as they relate to the number of births and deaths within a society or country. The DTM model looks at various external forces as well as social, economic, and political forces at play to classify populations within one of five stages. Countries progress through stages as populations change over time. Often, observing a particular country's stage within the Demographic Transition Model can better help understand the economic and social stability of the country. Higher stage countries generally have more stable population growth and thus a better social and economic platform to sustain and support the population.
In a country classified as Stage 5 in the DTM model, the population is usually high, but there are signs of a declining population. Usually, the birth rate will fall quickly in these countries and cannot keep up with the number of deaths. In a Stage 5 country example, the death rate may be as high as 9 per 1,000 people, but the birth rate is only 7 per 1,000 people. In this example, the number of new births cannot keep up with the number of aging and dying people.
In some rare cases, a negative population growth rate does not determine stage 5 DTM. In many countries in Europe, the birth rate is not enough to keep up with the death rate. However, the population continues to increase year after year. In this case, demographic changes usually result from immigration to a particular country, which is not accommodated in the DTM model. In these countries where immigration is artificially increasing the population, it will take two to three generations before the actual decline in population as a result of low birth rates is shown in population demographics.
Stage 5 population decline due to low birth rate is often related to better employment opportunities that may limit a woman's childbearing years or better education that can be connected to smaller family size. Other times, lower birth rates can result from a country enforcing child-producing limitations to help manage a growing population. A perfect example of a country exercising this control over the people in China's One-Child Policy used to prevent the exponential growth of the population.
Many countries have come to the point where their birth rate cannot keep up with the number of deaths. However, their population is inflated by many adults moving to the country. Because the Demographic Transition Model does not account for migration or immigration changes, these countries cannot be included in the Stage 5 DTM statistics. Primarily, countries that have been included with Stage 5 DTM numbers are Southern and Eastern European countries. Examples include Germany, Greece, Estonia, Croatia, Ukraine, and Portugal.
Japan is a Stage 5 country because currently, the birth rate cannot currently keep up with the country's death rate. More people die in Japan every year than are born.
There are currently approximately 7 DTM Stage 5 countries where the population is falling due to low birth rates when compared to death rates.