This narrowed the reproduction of the population – the resumption of the population in the shorter scale and TFR above 2.2 will determine the growth of the population – the expanded reproduction of the population in ever-increasing scale, as the number of parents will increase with each generation. The total fertility rate is not dependent on the age structure of the population, it affects only the rate of marriage.
In highly developed countries, the average TFR is 1.9, ie, slightly below replacement level, but their population is growing as a higher birth rate in the past has led to the fact that the current generation is quite numerous, and the number of births exceeds the number of deaths. But it is possible to predict the stabilization and then decline in population since the current generation of parents are aging, dying, and not completely replaced.
In less developed countries, the TFR in 1995 was 4.8, in 1998 – 3.3 percent, according to forecasts, in 2050 it will be equal to 2.1. Even if the TFR in developing countries would fall to replacement level (which is unlikely), their population for some time to grow before stabilizing. Thus, the population of developing countries has demographic potential doubling of the population in the near future.
A global effort in the field of family planning in recent decades have led to a significant decrease in the TFR. If this trend continues in the future, we can expect that the developing countries approach the level of reproducing simple birth around 2025. But given the current demographic potential of their people still grow significantly until 2080, while in developed countries, population growth will slow down or even stop.
Consolidated characteristic of birth is = gross reproduction rate (or gross) – an indicator of the reproduction of the female population. It shows the average number of girls who give birth before the end of one woman of reproductive age. Gross fertility can be calculated by the formula:
where fx – age-specific fertility rates,
- The total fertility rate, σ – the proportion of girls among newborns.
However, since not all the daughters reach the age of the mother, in which she gave birth to them, and not all of them survive until the end of fertile age, as the summary characteristics of the mode of reproduction using the net reproduction rate, which indicates how many daughters give birth in this mode of reproduction for throughout the life expectancy certain set of baby girls. Net rate (or net rate) characterizes the reproduction mode of reproduction including fertility and mortality. Calculated as follows:
where σ – the proportion of girls among newborns,’s – age, fx-age birth rate function, Lx – age function of survival women.
Net reproduction rate should be less than the gross rate because they vary depending on the level of mortality among women of childbearing age. Since in the present conditions the mortality rate of women of childbearing age is insignificant differences may occur mainly in tenths, ie range of variation values NRR in developed countries, about the same as the boundaries of the gross factor.
The overall mortality rate – (meter mortality rate), the ratio of deaths to the average population, expressed as a% of and is calculated as follows:
where T – the length of time in years, M – the number of deaths, S-average population.
The overall mortality rate depends on the intensity of mortality and the specifics of the current age-sex structure of the population. More accurate measuring instruments of death – age-specific mortality rates. They allow you to identify specific differences in mortality by age group.
Under the most favorable conditions the value of the crude death rate can not exceed 5.4% o. It is unlikely that, for relatively large groups of people within a year of its minimum value was zero. The same is the value of the crude death rate to calculate more complicated, but in the absence of control over its dynamics and spectacular any measures of disease control, we can assume it grows to about 50%. In 2000, the overall mortality rate was equal to 15.3% of (in 1990 – 11.2% o).
An important indicator in demography is the infant (child) mortality. It measures the mortality rate of children under one year shows the number of children who die within the first year of life in the ratio per 1,000 births. In contrast to the crude death rate, the number of deaths of children correlates with the number of births, but not with the average population.
Found that of all deaths of children under 1 year of about two thirds were born in the same calendar year, and about one third – in the year preceding the year of their death. If we denote: m0 – the infant mortality rate, M0 – the number of deaths under 1 year, N0-the number of births in a given year, TV j – the number of births in the past year, the expression for calculating the rate of infant mortality (Formula RATS) will be as follows:
To calculate this indicator in countries with low infant mortality rate is applied another relationship: