demography OBG

 Population dynamics is the branch of life
sciences that studies short-term and long-
term changes in the size and composition of
populations, and the biological and
environmental processes influencing those
changes.

Population studies are concerned not only with
population variables but also with relationships
between population changes & other variables –
social, economic, political, biological, genetic,
geographical, environmental, health.

 Size refers to the
number persons in the
population
 Distribution refers to
the arrangement of the
population in space at a
given time
 Structure is the
distribution of
population among its
sex & age groupings

Change is the growth
or decline of the total
population or one of
its structural units. The
components of change
total population are
births, deaths, &
migrations
Age-Sex Composition
of a population refers
to the proportion of
males & females in
different age-groups.

Net-Migration
refers to the total
number of persons
added or subtracted
from a population
as a result of the
combined effect of
immigration &
emigration

 Urbanization refers to mass
migration of rural population
into urban centers resulting in
increasing the urban
population & growth of cities
 Population Growth Rate (%/
year) is the rate at which a
given population is expected
to increase in a given period
of time.
 Population Doubling Time
refers to the time that would
take for a population to
double.

Replacement Level Fertility (or Zero
population growth) is activated when a
couple has two births during their
reproductive life, just enough to replace
themselves.

There are four ways in which the number of
people in an area can change during two time
periods t0 & t1
Pt1 = Pto + (B – D) + (IM – OM)
Thus the population of an area may change due
to natural reasons (B – D) known as natural
increase or due to migration (IM – OM) known
as net-migration.
Subsequently:
Population Growth = Natural Increase + Net
Migration

Composition is a property of a group of
people. It describes how the total given
population is constituted (e.g. 51% males,
20% below age 5, 85% healthy 7& 30%
employed etc).

Dependency Ratio
= Children + Elderly X 100
Working Age
= Pop below 15 + 65 & above X 100
Pop 15 – 64 years
Sex Ratio: The overall sex ratio is simply the
ratio of males to females in the population
Sex Ratio = Number of Males X 100
Number of Females

 Agriculture
 Economy and urbanization
 Food and nutrition
 Literacy and education
 Labor force and
employment
 Clothing and housing
 Health care services
 Water supply and
environment

 Social policies and social changes Involuntary
approaches to population control Family
planning approach to fertility control

Demography derived from two words
Demography is scientific study of human
population
Demos
+
graphy

MAJOR
SOURCES
OF
DEMOGRAP
HIC
DATA
CENSUS
REGISTRATION
OF VITAL
EVENTS
DEMOGRAPHIC
STUDIES
NATIONAL
SURVEY

 Changes in population size
 Composition of population
 Population distribution in space

Social mobility
Migration Marriage
Mortality
Fertility
5 demographic
processes:

EARLY
EXPANDING
LATE
EXPANDING
LOW
STATIONERY
DECLINING
HIGH
STATIONERY

 2.4% world land area & 17% of world’s
population
 2000- 11th May, 1 billion

Age and sex composition
Age pyramid
Sex ratio
Dependency Ratio
Density of population
Family size
Urbanization
Literacy & Education
Life Expectancy

Age & sex
composition
0-14 yrs male
population 1% more
than female, 60+
female population
0.6% more than male
Proportion < 15 yrs
decline, elderly >
burden on health
services.

 Age pyramid
broad base tapering top

Sex Ratio
No of females/1000
males
-mortality
-sex selective migration
-sex ratio at birth
2004 -06 892
0-4 yrs 908
Kerala only state with
1,058 females per 1000
males

Dependency Ratio
Total dependency ratio=
0-14 years +65 years and above
15 to 65 years
Societal dependency ratio
Density of the population
Number of persons living per square kilometer

Family size
The total number of
children a woman has
borne at a point in time.
Depends on:
 Duration of marriage,
education of couple, the
number of live births
and living children,
preference of male child,
desired family size etc.
Two child family norm

 Urbanization
Increase attributed to:
Natural growth, migration from
villages,
Attraction of better living
conditions availability of social
services.
Mega-cities- those with
population of 10 million or
more
Mumbai, Kolkata, Delhi
 Literacy and education
 Life Expectancy

 Statistics concerning the important events in
human life, such as births, deaths,
marriages, and migration

 Demography & vital events
 Health status-mortality , morbidity ,disability
& quality of life
 Health resources-facilities , beds , manpower
 Financial statistics

 Registration Method: This method
consists of continuous and
permanent -recording of births,
deaths, marriages, migration, etc
 Census
The census provide the vital
statistics information such as age,
sex, marital status, education level,
occupation, religion, etc.
However, these information
pertain to the census years only
(once in ten years)


Surveys are conducted in areas where the
registration method is not effective or not
functioning properly

 The field investigation consists of continuous
enumeration of births and deaths by a resident
part-time enumerator, generally a teacher followed
by an independent survey every six months by an
official. The data obtained through these
operations are matched
 Hospital records
 Epidemiological surveillance
 Disease registers

 The vital statistics help us in understanding how the
population profile of a country or a region within the
country is changing.
 2) The estimation of population trends and
projections help the policy planners & administrators
for better planning and evaluation of economic and
social development programmers.
 The mortality statistics help us to improve the health
conditions of the communities.


 Rationale for use
Neonatal deaths account for a large proportion
of child deaths. Mortality during the neonatal
period is considered to be a useful indicator of
maternal and newborn health and care

 Number of deaths during the first
28 completed days of life per
1000 live births in a given year or
period .it is of two types
 early neonatal deaths- occurring
during the first 7 days of life
 late neonatal deaths- occurring
after the 7th day but before the
28th completed day of life.

 Number of deaths of children
under 28 days of age in a year × 1000
 Total live births in a same year

 The death of a woman while
pregnant or within 42 days of
termination of pregnancy,
irrespective of the duration
and site of the pregnancy,
from any cause related to or
aggravated by the pregnancy
or its management, but not
from accidental or incidental

Total no. of deaths of women due to
complications of pregnancy ,childbirth
or within 42 days of delivery from puerperal
causes in an area during a given period × 1000
Total number of live births in the same
area & year

 Park k.; “Textbook of preventive and
social medicine”; edition 21st; published
by m/s banarsidas bhanot publishers;
page 850,858.
 Gulani k. K, community health nursing
principles & practises,1st edition,
published by pd11-12b,vishaka enclave,
pitampura, delhi-110034.

demography OBG

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