Birth Rate > Death Rate = Natural Increase in population ... · 9/6/2012 · Birth Rate > Death Rate = Natural Increase in population ... patterns of fertility, mortality, and migration

Community Medicine… Dr. Samar Al-Sharif… Sheet #6

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بسم اهلل الرمحن الرحيم

Last lecture we discussed various concepts concerning demographic studies, in

this lecture we’ll discuss some more concepts like: Mortality Rates, Life

Expectancy, Population Composition and Change.

** Numbers concerning countries other than Jordan are merely examples, not to

be memorized, nevertheless you should be able to understand the reasons

behind the differences in these numbers from country to country and relate them

to the level of development of these countries.

************

Mortality:

After we’ve finished talking about birth rates, this lecture will handle mortality

rates, both of which are related to the term natural growth.

Birth Rate > Death Rate = Natural Increase in population

Death rate > Birth Rate = Natural Decrease in population

When studying a population we can subdivide mortality rates into more specific

divisions that study mortality rates more accurately, like: Infant Mortality Rate

(newborns’ deaths), Maternal Mortality Rate (deaths as a result of complications

of pregnancy or childbearing) and so on.

We’ll begin talking about the most general of those which is the Crude Death

Rate: (The term “Death Rate” also refers to “Crude Death Rate”)

Death Rate: It is the average annual number of deaths during a year per 1,000

population at midyear.


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“The death rate, while only a rough indicator of the mortality situation in a

country (not sufficient to understand all aspects of mortality), accurately indicates

the current mortality impact on population growth.”

This means that although the crude death rate can’t be accounted to when

discussing mortality and its causes thoroughly, it can always be used in calculating

the population growth (number of births – number of deaths) because a death is

a death regardless of the age, sex or cause.

How to calculate crude death rate??

K: Usually 1000 to get the value (number of deaths per 1000)

Example: if the number of deaths in Turkey was 405,000 in the 1990s and the

total population was 61,644,000, then the crude death rate at ythat period of

time was??

Crude death rate = (405,000/61,644,000) *1000 = 6.6 deaths/1000

population

Crude death rate in Jordan:

The crude death rate has decreased significantly in Jordan in the last 50 years

even faster than fertility rates:

Early 1960s: 18 per thousand population

Early 1980s: 12 deaths per thousand population

2007: 7 deaths per thousand population

2011: 2.69 deaths per thousand population

This decline in the mortality rates indicates a massive improvement in

healthcare services…


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“Mortality rate is significantly affected by age distribution, and most countries will

eventually show a rise in the overall death rate, in spite of continued decline in

mortality at all ages, as declining fertility results in an aging population. “

Although the case seems to be that there is a decrease in mortality rates, this

decrease will eventually stop and mortality rates will start to rise again. The

reason behind this is that nowadays, communities are heading toward low fertility

(low number of newborns) and at the same time low death rates, which will lead

eventually to an aging population (population in which there is a significant

number of elderly), which will lead to an increase in death rates (because elderly

are more susceptible to death).

Example:

In the past only 3% of the population in Jordan were elderly. Now, 8% of the

population are considered elderly (65+ years old).

**********

* Death rates can also be age-specific or cause-specific or sex-specific.

* Age-specific death rates: Are death rates for each age group.

Eg: Infant mortality rate (death rate of newborns from birth till 1 year of

age) which is considered one of the most sensitive indicators of the health status

of a country, and it is the most sensitive indicator of the health status in Jordan,

whereas in other countries with better statistical figures other death rates can be

considered more sensitive in knowing a country’s

health status.

In the slides we have a chart that compares cause

specific death rates between more & less

developed countries.

As you can see the most common cause of

death in less developed countries is infectious & parasitic disease.

Whereas in more developed countries the most common cause of death is

Cardiovascular Disease (Circulatory system disease).


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In the next slide we’ve got another chart

that represents Age and Sex specific death

rates.

**Almost always male death rates are

higher than female death rates.

** You can notice that death rates increase in children less than 1 year of age

(infants) and people 65 years old or more (elderly)

***************

Infant Mortality Rate:

** This entry gives the number of deaths of infants under one year old in a given

year per 1,000 live births in the same year it is also included in the total death rate

and deaths by sex.

** This rate is often used as an indicator of the level of health in a country as it is

a sensitive indicator of death rate because newborns are fragile and have a high

probability to die during the first year of life.

How to calculate infant mortality rate?

IMR in Jordan:

2003 --- 22 deaths/ 1000 newborns

2007 --- 19 deaths/ 1000 newborns

2013 --- Expected to reach 17 deaths/ 1000 newborns


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Maternal Mortality:

** The maternal mortality ratio: is the number of women who die as a result

of complications of pregnancy or childbearing in a given year per 100,000 live

births in that year.

** Deaths due to complications of spontaneous or induced abortions are

included.

** A Maternal Death: the death of a woman while pregnant or within 42 days

of termination of pregnancy from any cause related to or aggravated by the

pregnancy or its management but not from accidental or incidental causes.

** Maternal deaths are much lower than infants’ deaths, thus it is estimated per

100,000 live births rather than 1000 live births as in IMR.

** 90% of the total number of maternal deaths occur in developing countries.

** Maternal mortality rate reflects the level of maternal healthcare services

provided in a given country. These services include: Prenatal (preceding birth),

Delivery and Postpartum (after birth) services.

** Maternal mortality rates can be:

As low as 1-2 maternal deaths/ 100,000 live births in developed countries

up to 350-370 maternal deaths/ 100,000 live births in developing countries.

**Maternal mortality RATIO = maternal mortality RATE

How to calculate maternal mortality ratio??

Where K = 100,000 not 1,000 as in infant mortality rate.


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Life Expectancy:

** life expectancy reflects general health services provided for the population, as

the longer the life expectancy the better the health services provided.

** As life expectancy increases, the number of elderly in the population increase,

as a consequence chronic diseases (Alzheimer’s disease, hypertension, diabetes

etc…) become more common.

** Life expectancy is: an estimate of the average number of additional years a

person could expect to live if the age-specific death rates for a given year

prevailed for the rest of his or her life.

Eg: If the life expectancy for 1996 remain unchanged, males in Brazil born in

1998 can expect to live 64.1 years on average; females can expect to live 70.6

years

** Life expectancy is a hypothetical measure because it is based on current death

rates and actual death rates change over the course of a person’s lifetime.

** Each person’s life expectancy changes as he or she grows older and as

mortality trends change

** There is NO formula for calculating life expectancy.

Life expectancy in Jordan:

Mid 1960s: 49

2009: 72.9

2011: 74.2

This increase in the life expectancy in Jordan is a result of better health services,

better environmental health, better living conditions, etc…

** Life expectancy for females is usually higher than that for males.


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** Age and sex are the most basic characteristics of a population.

** Every population has a different age and sex composition: The number and

proportion of males and females in each age group.

** This structure can have considerable impact on the population’s social and

economic situation, both present and future.

** In nature, number of males is higher than that of females, nevertheless in the

case of wars the number of the males and females may become equal.

** Young and old populations have markedly different age compositions; as a

consequence, they also have different proportions of the population in the labor

force or in school, as well as different medical needs, consumer preferences, and

even crime patterns.

Median Age:

** A population’s age structure has a great deal to do with how that population

lives.

** The median age is the age at which exactly half the population is older and half

is younger.

** Examples:

* The median age of the Costa Rican population in 1995 was 23 years.

* In 1995, the median age in Jordan, with a young population, was 18, which

means that have the population then were above 18 and the other half under 18

* While that in Sweden was 38, signifying an older population.


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Sex Ratio:

In most cases, at birth the number of males is higher than that of females, but as

a consequence of higher death ratios of males than that of females this statement

may be changed overtime.

Population Pyramid:

** A population pyramid graphically displays a population’s age and sex

composition.

** Horizontal bars present the numbers or proportions of males and females in

each age group.

** The sum of all the age-sex groups in the population pyramid equals 100

percent of the population.

In the slides we’ve got an example about the

population pyramid that compares between

developed and developing countries

In less developed countries you can notice

the presence of a wide base and a thin apex

which implies high fertility rates and high

death rates.

While in more developed countries you’ll notice that the apex is nearly as wide as

the base and the middle age is the most common. This implies low fertility rates

and low death rates.

Jordan’s Population Pyramid:

** The base of the pyramid is decreasing in

width with time as a result of lower fertility

rates.

** The apex is increasing in width with time as a result of lower death rates.


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Population Profiles:

** The main three variables that change the population are:

Fertility(birth rate), Mortality(death rate) and migration

** Populations of countries can differ markedly as a result of past and current

patterns of fertility, mortality, and migration. However, they all tend to fall into

three general profiles of age-sex composition.

1. Rapid growth is indicated by a pyramid with a large percentage of people in the

younger ages. In the population pyramid you can identify it by a wide base, like

that of Jordan.

2. Slow growth is reflected by a pyramid with a smaller proportion of the

population in the younger ages, just like the population pyramid of USA that we’ll

see in a moment.

3. Zero growth or decreasing populations are shown by roughly equal numbers of

people in all age ranges, tapering off gradually at the older ages, just like the

population pyramid of Spain that we’ll see in a moment.

*****************

-In the next 3 slides we’ve got a comparison between the population pyramids of

three countries with different population profiles: Nigeria, Spain and USA.

** In the population pyramid of Nigeria we can notice a fast growing growth

profile indicated by a wide base.

** In the population pyramid of Spain we can notice a zero or declining growth

profile indicated by nearly equal widths of the apex and base (low fertility).

** In the population pyramid of USA we can notice a slow growth profile

***** In Jordan we’ve got a fast growing profile indicated by a wide base and

thin apex.


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Population change:

** Population change has three components: births, deaths, and migration.

** As people are born, die, or move, their total numbers in an area change.

** During most of history, world population increased very slowly, but during the

20th century, this growth has accelerated.

** Migration has two components: Emigration & Immigration

Emigration: is the movement of individuals outside a country. (out migration)

Immigration: is the movement of

individuals into a country. (in migration)

In the next slide we’ve got a graph that

compare between more and less

developed countries in terms of

population growth.

We can notice that less developed

countries have a much faster population

growth due to high fertility rates.

Population Change:

A change in population size over a given period of time equals the number of

people in the population at the beginning of the period plus any births that

occur during the period, minus any deaths, plus net migration during the period.

Rate of Natural Increase:

** The rate of natural increase is the rate at which a population is increasing (or

decreasing) in a given year due to a surplus (or deficit) of births over deaths,

expressed as a percentage of the base population.

** Net migration is the number of immigrants minus emigrants.


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Growth Rate:

** Growth rate can represent an increase or decrease in the population. (Not

necessarily an increase).

** it can represent a decrease in the population in the case of low fertility rates

and low life-span.

** The growth rate is the rate at which a population is increasing (or decreasing)

in a given year due to natural increase and net migration, expressed as a

percentage of the base population.

** The growth rate takes into account all components of population growth:

births, deaths, and migration.

** –

** It should not be confused with the birth rate.

Examples:

With an annual growth rate of 1.82 percent in 1996, the United Arab Emirates

would require about 38 years to double its population.

Uganda would take 24 years, at 2.9 percent.

Belgium, at its present low annual growth rate of 0.5 percent, would take several

centuries to double its population.

**** Jordan :

Growth rate: 2.8

Natural growth: 2.3

This difference between the growth rate and natural growth is due to taking Net

Migration into consideration when calculating the growth rate and not taking it

into into consideration when calculating the natural growth. Thus we can say that

0.5 (2.8-2.3=0.5) of the growth rate is due to migration.


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Population Change:

** The change in population size accounted for by more births in the population

than deaths is referred to as "natural increase."

** The term "natural decrease" refers to population decline resulting from more

deaths than births.

The Demographic Transition:

** The demographic transition refers to: the change that populations undergo

from high rates of births and deaths to low rates of births and deaths.

** High levels of births and deaths kept most populations from growing rapidly

throughout most of time, which means that the high death numbers can be

compensated with high fertility rates and vice versa.

** Why doesn’t the population change dramatically in the world??

Because throughout history communities with high birth rates also have high

death rates (less developed countries), and those with low birth rates also have

low death rates (more developed countries).

Developed countries: low fertility & low mortality, no significant change in the

population.

Developing countries: high fertility & high mortality, no significant change in the

population.

The End Your colleague: Mohammad Al-Jabaiti

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Birth Rate > Death Rate = Natural Increase in population ... · 9/6/2012 · Birth Rate > Death Rate = Natural Increase in population ... patterns of fertility, mortality, and migration