1. Fertility and Mortality (9 Jan 07)

8/2/2019 1. Fertility and Mortality (9 Jan 07)

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FERTILITY AND MORTALITYFERTILITY AND MORTALITY

CRP II


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FERTILITY

FERTILITY

refers to the number of live births women have

FECUNDITY

refers to the physiological capability ofwomen to reproduce

Fertility is directly determined by a number of factors that,

in turn, are affected by a great many social, cultural,economic, health and other environmental factors


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BIRTH RATE

The Birth Rate = Crude Birth Rate (CBR)

Indicates the number of live births per 1,000 population ina given year

Numberof live births

Mid-yearpopulationx k =

38,868

1,620,086x 1,000 = 24.0

e.g.

There were 24 births per1,000 population in Kuwait in 1984

Around the world BR vary widely


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GENERAL FERTILITY RATE = FERTILITY RATE

GFR is the number of live births per 1,000 women ages15-49 in a given year

GFR is somewhatmore refined measure than the BR,because it relates births to the age-specific group at risk ofgiving birth (women ages 15-49)

#of

live

births 181,268

x 1,000 = 62.0

# women ages 15-49 2,923,344

x k =

There were 62 births per1,000 women ages 15 49 in Equador

in

1995


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AG

E-SPECIFIC FERTILITY RATE (ASFR)

# ofbirths to women ages 20-24 23,694

x k = x 1,000 = 81.4

# ofwomen ages 20-24 290,998

e.g

In Austria in 1994, there were about 81,4 live births forevery

1,000 women ages 20-24.


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Compare the fertility rates for women in Puerto

Rico in the different age group belowAges

Year 20-24 25-29 30-34

1965 257.4 189.6 114.1

1975 154.9 146.1 91.2

1985 146.3 132.0 70.6

1994 133.8 113.5 69.6

In Puerto Rico in 1994, there were 134 live births to women

ages 20-24 per1,000 women in that age group


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TOTAL FERTILITY RATE

TFR is the average number of children that would be

born to a woman by the time she ended childbearing,if she were to pass through all her childbearing yearsconforming to the ASFR of a given year


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Calculate the TFR : A countrys TFR, 1994

Age ofwomen

(1)

# ofwomen

(2)

# of birthsto that age

group

(3)

Birthsrate

(2) : (1)

(4)

ASFR

(3) X 5

15 - 19 244,000 4,474 .018 .090

20 - 24 225,800 28,013 .124 .620

25 29 194,200 36,440 .188 .940

30 34 182,300 27,402 .150 .750

35 39 181,400 14,044 .077 .385

40 44 177,600 3,176 0.18 .090

45 - 49 151,100 182 .001 .005

Sum 2.88


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In some developing countries the TFR is > 5 children

In most developed countries the TFR is < 2


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GROSS REPRODUCTION RATE (GRR)

GRR is the average number of daughter that wouldbe born to a woman (or a group of women) duringher lifetime, if she passed through childbearing

years conforming to the ASFR of a given year

GRR TFR~

daughter measures reproduction


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NET REPRODUCTION RATE (NRR)

NRR is the average number of daughters that wouldbe born to a woman (or group of women) if shepassed through her lifetime from birth conforming

to the ASFR and mortality rates of a given year

NRR GRR~

It is lower because it takes account the fact thatsomewomen will die before completing their childbearing

years


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Country GRR NRR

Burkina Faso 3.50 2.41

U.K. 0.86 0.85

1993

That means that if 1993 fertility levels were to continue, awoman in BF would produce 3,5 daughters, on average,during her lifetime.

In the UK, by contrast a woman would produce < 1daughter on average her lifetime.

In BF: 1 daughter would die, on average before completingher childbearing years.


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MORTALITY

Mortality refers to deaths that occur

within a population

While we all eventually die, the probability of dying duringa given time period linked to many factors, such as age,

sex, race, occupation and social class.The incidence of death can reveal much about populationsstandard of living and health care.


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Mortality data

Limitations of mortality data

Sources of mortality data

Systems

Shortcomings in the system

System improvement

Definitions of mortality rates

1

2

3

4

5

6

7


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(a) Vital Statistics

Data on various vital events of human life,such as :

- births - marriages

- stillbirths - divorces

- deaths - etc.

1 Mortality data


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(b) Mortality statistics

(c) The use of mortality and fatality rates in the

following context:

- comparative assessment of community health

- assessment of health needs of the people andfixing priorities for action in terms of reducing

risks of death

- remodelling and strengthening of health

services

- Evaluation of health programmes


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- measurement of relative importance of specificdiseases/conditions as causes of death

- estimation of average span of life that an

individual of a specified age is likely to attain.

- assessment of the efficacy of a drug or procedure

in a clinical therapeutic trial against a disease/

condition, particularly one for which fatality is high

(such as bubonic or pneumonic plague).


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Use alone, mortality data do not reveal the levels of

health of a group of people who are alive.

Detailed cause-specific mortality data are of limited

use in the absence of reliable statistics on births,

deaths, and demographic aspects aspects, preferably

by geographical and/or social subgroups.

2Limitations of mortality data


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Vital registration system

National sample surveys

Special health surveys

Hospital records

Notification of infectious diseases

Government health institutions

Voluntary health institutions

Revenue agencies

Police

Village/community councils

Reports of national and international organizations

3 Sources of mortality data


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- Systems for recording, reporting and registering

deaths and fetal deaths, covering:

- registration of deaths and stillbirths

- differences in methods used forR-R-R

deaths from country to country

- the various agencies responsible for

registering deaths, according to legal

provisions of the country

- A uniform system of registering deaths is

necessary for national and international

comparisons

4 Systems (R-R-R)


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Shortcomings in the R-R-R of deaths and fetal deathsmay occur through:

- incomplete data;

- lack of uniformity in collection/reporting such data;

- lack of uniformity in definitions and criteria of events and

rates;

- lack of accuracy, particularly in respect ofage at, and

cause of, deaths.

5 Shortcomings in the system


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A number of suggestions for possible improvement in

the system :

- Compulsory registration of deaths;

- Establishment of a uniform system throughout

the country;

- Health education to promote recognition of the

significance and usefulness of such data by the

primary reporting agency;

- Use of special sample surveys to check extent

and accuracy of registration of deaths by

regular agencies;

- Training of persons certifying deaths.

6 System improvement


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(a) Crude death rate (CDR)

Total no.of deaths due to all causes occurring

in a defined area during a defined period

CDR =

Estimated totalpopulation at risk in the same

area during the same period

x k

D

CDR = X 1000

P(est. mid-year population)

7 Definitions of mortality rates

10n


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The merits and demerits of the CDR:

It measures the average risk of death in thepopulation at large

It is easy to compute

Its level reflects not only mortality risks but alsothe age and sex composition of the population.

Hence it can be used to compare relative mortality

in two populations if they have a similar age/sex

composition

It is often used forcomparing relative mortality in a

given area between two periods of time that are not

too far apart


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- It takes no account of the fact that the chance of

dying varies according to age group, sex, race,

occupation, etc.


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(b). Age- and sex-specific death rate (ASDR)

Total no. of deaths occurring in a specific age and sexgroup of the population of a defined area during a

defined period

Estimated total population ofthe same age and sex

group of the population of the same area during thesame period

=x k


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The merits and demerits of the ASDR

- It measures risk of death among persons in a specific

age and sex group

- It is simple to calculate

- It does not summarize total mortality in a single

figure.

- It can be used to compare the mortality of two

populations of the same specific age and sex group,

even when the age and sex compositions of these

populations are different.


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- It takes no account ofdifferences in the population

structure in terms of race, occupation, religion, etc.

-It gives the essential components forconstructing life-tables.

- Comparison of overall mortality conditions in the two

populations is cumbersome, because of the need to

compare rates for all the different age groups and for

males and females.


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(c) Stillbirth rate (Late fetal death rate)

Measures the risk of fetal death occurring

after 28 completed weeks of gestation

No. of stillbirths occurring in a specified area

and period of time

No. of live births and stillbirths occurring in

the same area and period

=x k


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(d) Perinatal Mortality Rate

Measures the risk of death occurring either during

pregnancy after 28 completed weeks of gestation or

within 1 week after delivery

No. of perinatal deaths*) occurring in a

specified area and period of time

No. of live births and stillbirths occurring in

the same area and period

= x k

*) no. of stillbirths + no. of deaths of infants under 1 week of age


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(e). Neonatal Mortality Rate

Measures the risk of dying within 28 days of birth

No. of deaths of infants under 28 days of age occurringIn an area during a given period

No. of live births in the area during the same period

x k=


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(f). Post-Neonatal Mortality Rate

Measures the risk of dying during infancy after the first 4

weeks of life

No. of deaths among infants aged 4 weeks to 1 yearoccurring in a specified area and period

No. of live births in the same area and period

x k=


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(g). Infant Mortality Rate

Measures the risk of dying during infancy

(i.e. the first year of life)

No. of deaths of infants under one year of age occurringIn an area during a given period

No. of live births in the same area during the same period

x k=


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(h). Maternal Mortality Ratio

Measures the risk of women dying from maternal causes

Total no. of maternal deaths due to complications ofpregnancy, childbirth and the puerperium

in an area during a given period

Total no. of live births in the same area and period

x k=

K= 100,000


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(j). Case Fatality Rate (CFR)

Is useful in measuring how fatal a disease/ condition is

Total no. of deaths due to a given disease/conditionOccurring in an area during a given period

Total no. of persons who suffered from the same

disease / condition in the same area during the same period

x k=


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28 weeks

Delivery

1 week

28 days

1 yr

PMR

NMRPNMR

IMR

Gestational

age

SR


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References

1. Population Reference Bureau.Population Handbook,

5 ed., 2004

2. S.K. Lwanga and Cho-Yook Tye (ed.). Teaching Health

Statistics : twenty lesson and seminar outlines. Geneva:

World Health Organization,1986

1. Fertility and Mortality (9 Jan 07)

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