What is a Rate of Natural Increase?

The rate of natural increase is calculated by determining the difference between birth and death rate.
The rate of natural increase is calculated by determining the difference between birth and death rate.

Every day around the globe, some children are born and some people die due to various different reasons. The rate of natural increase refers to the difference between the crude birth rate and the crude death rate of a given population. Crude birth rate refers to the total number of live births annually among a population of 1,000 mid-year population. Crude death rate, on the other hand, relates to the total number of mortalities who die for whatever reasons per 1,000 persons. When calculating the rate of natural increase, it is recommended to exclude both the out-migration and the in-migration.

How is the Rate of Natural Increase Calculated?

The formula used to derive the rate of natural increase is conventional to avoid contradicting values from countries all over the world. The World Health Organization (WHO) obtains all the calculated values for each country worldwide to help them plan on how to aid various countries. The alarming increase in Sub-Saharan African populations due to slow infrastructural development affects their rate of natural increase. WHO uses the values of the rate of natural increase to evaluate what monetary, human resources, and technical assistance they can provide to such countries.

The rate of natural increase equals;

{Crude Birth Rate-Crude Death Rate}/10

The values of the rates of birth and death are for every 1000 people and the solution of the calculation is in percentage form.

Example of a rate of natural increase calculation

If a country has a crude birth rate of 36.79 and a crude death rate of 6.95 then;

The rate of natural increase = {Crude birth rate – Crude death rate}/10

= {36.79-6.95}/10

= 2.984%

Hence, the rate of natural increase of the country becomes 2.984%.

According to global statistics in 2016, the average global crude birth rate is 18.5 per 1,000 persons whereas the average crude death rate is 7.8 per 1,000 annually. As a result, the average global rate of natural increase in 2016 was 1.07%.

What is the Difference Between Population Growth and the Rate of Natural Increase?

As mentioned earlier, when determining a country’s rate of natural increase, the factors taken into consideration are the birth rates and death rates only. However, studies show that the fertility of the population also affects the birth rates. On the other hand, the social amenities such as health institutions affect mortality rates. In-migration and out-migration are excluded in the calculation of the rate of natural increase. Population growth, however, is more practical and includes the migration patterns of the people in a given population. Studies show that the migration patterns have effects on the rate of natural increase too, though to a lesser extent. In-migration increases the rate of natural increase whereas out-migration reduces the rate of natural increase.

​Importance of the Rate of Natural Increase

The rate of natural increase is significant for each country. It is required for the implementation of projects and planning for the population. In the Demographic Transition Model (DTM), the rate of natural increase is used to rank countries based on their population growth rate cycles. Demographic studies give explanations on how the population growth rate is related to the economic development of a country or region.

Developed countries and developing countries have a clear distinction based on the rate in which their populations grow. The population growth of developing countries is higher than those of the developed countries. The increased populations experience challenges such as poor planning and a lack of adequate resources. Developed countries such as Germany and China exhibit negative or neutral rate of natural increase. In these countries, there are legislations put in place to limit the number of children born to a family. Such legislation assists the countries in planning for their population. Consequently, citizens of these countries receive adequate resources.

Demographic Transition Model (DTM)

Ironically, most of the developed countries still experience a rise in population in spite of the neutral or negative rate of natural increase. The cause of the high growth is the massive influx of immigrants. In spite of the influx, the resources are still adequate because of the low mortality. As a result the nations enjoy higher life expectancy. Besides, the residents receive sufficient medical care whenever they fall sick. The demographic transition model is the model that helps in the description of the death rates.

There are five stages in the DTM. The developing countries occupy the earlier stages 1-3 in the DTM. They hold this group due to their high fertility which translates directly into elevated crude birth rates. Developed countries mostly occupy stages 4 and 5 of the model and have lower but stable productivity. The low fertility rates result in lower population growth compared to developing countries. The causes of high mortality rates in developing countries are acute illnesses whereas populations of developed countries mostly die from chronic diseases. Due to this, the former experience higher death rates than the latter.

​Factors Affecting Rate of Natural Increase

A country’s infrastructure is one of the key factors that can affect the rate of natural increase. This effect occurs when government policies work hand-in-hand with the infrastructure. The policies implemented can either result in an increase in birth rates or a steady reduction of birth rates per annum. For instance, China came up with a system whereby each family should have only one child. It was a strategy to reduce the birth rates, the rate of natural increase and thus result in a drop in their population. The strategy was due to the imbalance between birth rates and death rates. China’s policy has been successful since it is now a developed country that can provide necessary services to its population resulting in reduced mortality rates.

Good infrastructure in developed countries is associated with the best services that support lives of their citizens. Their citizens can comfortably support families, provide adequate maternal and child health care, ensure healthy lives for its women, and give them the best education. With all these in place, death rates and maternal mortality rates are likely to drop.


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