Birth Rate vs Fertility Rate
Birth rate and fertility rate are very closely related terms that are very important in population biology. Despite their close relationship, the exhibited differences between them are important to consider, and those are prominent. From the definitions of the two terms, it would not be difficult to understand that birth and fertility rates have two focuses, but in the same population.
The term birth rate could be defined as the rate at which the births take place in a population during a particular time or period. Since it is a rate, the involvement of time for the number of births is very important. Usually, the period is defined for a calendar year (from 01st of January to 31st of December of a particular year).
Births, deaths immigrations, and emigrations take place in any population. Along with these factors, the growth of the population is determined, and the birth rate is very important for that. For humans, the birth rate is determined through the universal system of registration of births, deaths, and marriages. Birth rate is also known as the Natality, and the death rate is known as Mortality. The birth rate has been derived into the Crude Birth Rate (CBR), which is the number of births take place per one thousand individuals in a population. Usually, the CBR is calculated to measure the human population growth.
Birth rate or natality is important for the resource partitioning, as the available resources will be divided among individuals in a population, but the share of an individual decreases when the number of births increase. Additionally, the intraspecific competition increases with an increasing natality. Therefore, there should be a measure to control competition; mortality and immigration are some of those control measures of population growth to reduce competition.
When humans are considered, the natality has always been increasing with lowering mortality, causing an ever-increasing competition among people, but there is no sign of halting so far; instead, human birth rate causes additional problems for other species as well as for its own kind.
Fertility rate, aka total fertility rate or period total fertility rate, is an individual-specific parameter of a female, which measures the average number of children / offspring a female could give birth to over her entire lifetime. The fertility rate has been defined for a female if she would be to experience the usual age-specific fertility rates throughout her lifetime and survives throughout her reproductively viable period.
Fertility rate is an excellent indicator of the population growth, as the number of individuals increase with the increasing fertility rate until there are enough resources. Fertility rate describes the capability of females to produce offspring during their childbearing years, which is 15 – 49 for the humans. Not all women have exactly the same potential to give birth to kids, but it varies significantly across a population. Therefore, the average number is calculated, which means that the fertility rate applies for a hypothetical female based on actual information.
The fertility rate varies significantly across different countries with developed nations have low rates (1 – 2 or 2 – 3 children per female) and developing nations have high rates with sometimes up to 7 – 8 children per woman.
What is the difference between Birth Rate and Fertility Rate?
• Birth rate is a parameter of the entire population, while fertility rate is a parameter of a group of individuals in the population.
• Fertility rate determines the birth rate but, not the other way around.
• Fertility rate applies for females in the reproductive age, but there is no such restriction for birth rate.
• Birth rate is expressed in relation to a time interval, while fertility rate is expressed in relation to the number of females in the reproductive age.