8.1 Measurement of birth rate

The birth rate is measured by the general birth rate, in which the annual number of births is divided by the mean population and multiplied by one thousand. The general birth rate can also be calculated from a longer time span, such as five years. Then an average is calculated from the number of births, which is expressed as a proportion to the mean population of the period, and the derived figure is multiplied by one thousand.

As the name implies, the general birth rate describes the development of births very generally. The term "crude birth rate" may illustrate better that it is a very rough measure. Especially when the general birth rate is used to compare different countries with one another, different age structures of populations influence the result.

For a population that has a large number of old people and a clear male majority, the general birth rate may imply that the birth rate is lower than it in fact is. This is because the mean population actually contains much of such population that is not subject to the risk to give birth.

An advantage of the general birth rate is that it can be calculated fast. It should not be used for any far-going conclusions on how large or small the birth rate is because age structures are very different in various countries. In contrast, the general birth rate can be safely used for measuring the birth rate in one country in different years because changes in age structure are slow.