Crude birth rate

Also called: CBR · Topic: World Population: Distribution, Density, Growth and Migration · NCERT: Class 12, Ch 2 "The World Population: Distribution, Density and Growth"; Class 12, Ch 1 "Population: Distribution, Density, Growth and Composition"

Meaning

The crude birth rate (CBR) is the number of live births in one year for every 1,000 people in an area, counted against the mid-year population. It is one of the two basic measures of population change, along with the crude death rate (CDR). Subtract the CDR from the CBR and you get the natural growth rate, which tells you how fast a population grows without migration.

Explanation

How it is worked out

• Formula: CBR = (B ÷ P) × 1,000
• B = number of live births in the year.

• P = the estimated mid-year population of the area, usually counted on 1 July.

• Why the mid-year population?

• The population keeps changing during the year.
• The middle of the year is the best average of the people living there.

• The UN uses the same rule. It divides yearly births by the population at the middle of the period and shows the result per 1,000 people per year [2].

• Worked example (made-up figures):

• An area has 30,000 live births and a mid-year population of 15,00,000.
• CBR = (30,000 ÷ 15,00,000) × 1,000 = 20 per 1,000.

Where CBR fits in population change

• There are three components of population change: births, deaths and migration.
• Births add people. The CBR measures this part.
• Deaths remove people. The CDR measures this part.

• Migration moves people from one place (the origin) to another (the destination).

• Natural growth rate = CBR − CDR, per 1,000 people. It leaves out migration.

• Example: CBR 20 − CDR 7 = 13 per 1,000 = 1.3% a year. To get a percentage, divide by 10.

• For the whole world, migration cancels out. So world population changes only through the CBR and the CDR.

• Basic balancing equation: population at the end = population at the start + births − deaths + in-migrants − out-migrants.

Why it is called "crude"

• It divides by the whole population.
• The total includes men, children and old people, and none of them can give birth.

• It ignores age structure (how many people are in each age group).

• Result: the CBR depends on how many young women there are, not just on how many children each woman has.

• A young population has many women of childbearing age (15-49), so its CBR can be high.

• An old population has few such women, so its CBR is low.

• Better measures of fertility:

• Total fertility rate (TFR): the average number of children a woman would have in her lifetime at today's birth rates for each age. It does not depend on the age structure.
• Age-specific rates: births per 1,000 women in one age group (for example, women aged 20-24).

How CBR changes over time

• The demographic transition is the shift from high birth and death rates to low birth and death rates as a society develops.
• Death rates fall first. Better food, clean water, vaccines and medicine cut the CDR.
• The CBR stays high for some time. The gap between births and deaths widens.
• Population grows very fast. This was the "population explosion" of the developing world after about 1950.

• Later, the CBR also falls and growth slows.

• India's pattern (NCERT):

• Up to 1981: death rates fell fast but the CBR stayed high. Population grew very fast.
• After 1981 (fourth phase): the CBR started falling. Growth slowed, though it stayed high.

• Why the CBR fell: women married later (a higher mean age at marriage), and life improved, especially through female education.

• Population momentum (growth that continues after fertility reaches replacement level):

• Past high fertility left many young people.
• Many women are still entering the childbearing ages, so the number of births stays high even though each woman has fewer children.
• So the CBR can stay fairly high even when the TFR has fallen. Momentum will cause 79% of world population growth up to 2054, about 1.4 billion people [2].

Where it occurs

• High birth rates (high fertility):
• The Sahel and other parts of sub-Saharan Africa: Niger, Chad, Somalia, Central African Republic, DR Congo. Each has a TFR above 5.
• About one-fifth of fast-growing countries have a TFR of 4 or more. All are in sub-Saharan Africa except Afghanistan [2].

• These countries are in stage 2 of the demographic transition (deaths have fallen but births are still high). In the Sahel, population may double between 2024 and 2054.

• Low birth rates (ultra-low fertility, TFR below 1.4):

• China, Italy, Republic of Korea, Spain [2].

• Lowest of all: Republic of Korea and Hong Kong SAR (China), with a TFR below 0.75 [2].

• Birth rate below death rate (CBR < CDR, negative natural growth):

• China, Germany, Japan and the Russian Federation [2]. Their populations have already peaked.

• Low fertility, but population still growing through immigration:

• Canada, Luxembourg, UAE [2].

• India:

• The national TFR fell from 2.2 (NFHS-4, 2015-16) to 2.0 (NFHS-5, 2019-21), below replacement level [3].
• High fertility: the Hindi heartland (Bihar, Uttar Pradesh, Jharkhand) and Meghalaya. Bihar is the highest at 2.98 [3].
• Low fertility: the southern States, West Bengal, Punjab and the Himalayan States. Sikkim is the lowest.
• India is still projected to grow through 2054 because of momentum from its young population [2].

Don't confuse with

• Crude death rate (CDR): deaths per 1,000 people a year. The CBR counts the people who are added, while the CDR counts the people who are removed. Both use the mid-year population.
• Total fertility rate (TFR): children per woman over her lifetime, so it is not "per 1,000 people". It does not depend on age structure, while the CBR does. This makes the TFR the better measure of fertility.
• Natural growth rate: this is CBR − CDR, not the CBR alone. It also leaves out migration.
• Replacement-level fertility: this is a TFR value (about 2.1), not a CBR value. A country can reach it and still have enough births to keep growing, because of population momentum.

Prelims Hooks

• CBR = (live births ÷ mid-year population) × 1,000. Trap: the denominator is the population on 1 July (mid-year), not the population on 1 January or the Census count.
• The CBR is "crude" because it divides by the whole population and ignores age structure. A young population can have a high CBR even when each woman has few children.
• Natural growth rate = CBR − CDR. It leaves out migration. 20 − 7 = 13 per 1,000 = 1.3% a year.
• CBR lower than CDR (negative natural growth): China, Germany, Japan, Russian Federation [2].
• India (NCERT): the CBR stayed high until 1981. Its fall after 1981 was linked to a higher age at marriage and female education.
• For the world as a whole, population changes only through births and deaths, because migration cancels out.

Mains Points

• A falling CDR with a high CBR caused the population explosion.
• Public health cut deaths before births fell, so the gap widened. This is stage 2 of the demographic transition, seen today in the Sahel (Niger, Chad).

• Policy needs to bring the CBR down through girls' education, later marriage and family planning, as India's post-1981 experience shows (GS-I: population and associated issues).

• Crude rates can mislead planners.

• A young age structure keeps the CBR high through population momentum, even when the TFR is below 2.1. This is why India's population is still growing even though its NFHS-5 TFR is 2.0 [3].

• Planners should read the CBR together with the TFR and age-specific rates.

• Different regions need different policies.

• The high-fertility north (Bihar 2.98 [3]) needs family planning and girls' education.
• Low-fertility States, such as the southern States and Sikkim, need to prepare for an ageing population. East Asia and southern Europe already face this, with ultra-low fertility, shrinking workforces and dependence on immigration.

Related concepts

• Components of population change
• Crude death rate
• Total fertility rate
• Replacement-level fertility

Read more

• Components of population change: births and deaths