lecture II
المادة الدراسية:
(II)
Magnitude of the population problem all over the world
It required all the human history up to the year 1800 for the world population to reach one billion. The second billion came in 130 years, the third billion in 30 years, the fourth billion in 15 years, the fifth year in 12 years, and the sixth billion in 12 years. In 1999, world population became 6 billions, and is expected to reach 8 billions by 2025. It is projected that world’s population is most likely to reach 10 billions by 2050 and 20.7 billions a century later. World population has been growing at 176 people per minute, 10.564 people per hour, 253.542 people per day, and 92.543.000 people per year.
About three fourths of the world’s population lives in the developing countries. The rampant population growth has been viewed as the greatest obstacle to the economic and social advancement of the majority of people in the underdeveloped countries.
Demographic cycle:
1- First stage (high stationary):
High birth rate and high death rate cancel each other and population remains stationary.
2- Second stage (early expansion):
Death rate begins to decline possibly as a result of improved health conditions, while birth rate remains unchanged.
3- Third stage (late expanding):
Death rate declines still further and the birth rate tends to fall. The population continues to grow because births exceed deaths e.g China and India.
4- Fourth stage (low stationary):
Low birth rate and low death rate with the result that population becomes stationary e.g most industrialized countries.
5- Fifth stage (declining):
The population begins to decline because birth rate is lower than death rate e.g. Germany.
Growth rates:
When the crude death rate is substracted from the crude birth rate, the net residual is the current annual growth rate. The growth rate is not uniform in the world. These differences in growth rates are largely the result of fertility and mortality patterns. Approximately 95% of this growth is occurring in the developing countries. One third of the world’s population is under the age of 15 years and will soon enter the reproductive period giving more potential for population growth.
Factors affecting fertility:
1- Age at marriage.
2- Duration of marriage.
3- Use of contraceptives.
4- Spacing of children.
5- Religious matters.
6- Place of women in the society.
7- Traditional ways of life.
8- Level of literacy.
9- Level of living (economic status).
10- Value of children in the society.
11- Widow remarriage.
12- Breast feeding.
13- Customs and beliefs.
14- Industrialization and urbanization.
15- Health condition.
Fertility measurements:
By fertility, we mean the actual bearing of children. A woman’s reproductive period is roughly from 15 and 45 years, a period of 30 years and may give birth to 15 children, but this maximum is rarely achieved.
Fertility may be measured by a number of indicators as follows. Still births, fetal deaths and abortions are not included:
1- Crude birth rate:
The number of live births per 1000 estimated mid-year population. It is an unsatisfactory measure because the total population is not exposed to child bearing.
2- General fertility rate:
The number of live births per 1000 women in the reproductive age (15-49) in a given year. It is a better measure of fertility as the denominator is restricted to women in the reproductive age. the major weakness is that not all women are exposed to the risk of childbirth.
3- General marital fertility rate:
The number of live births per 1000 married women in the reproductive age (15-49) in a given year.
4- Age specific fertility rate:
The number of live births in a year to 1000 women in any specified age group. It is a more précised measure of fertility throwing light on the fertility pattern.
5- Age specific marital fertility rate:
The number of live births in a year to 1000 married women in any specified age group.
6- Total fertility rate:
The average number of children a woman would have if she were to pass through her reproductive years bearing children at the same rates as the woman now in each age group. It is computed by summing the age-specific fertility rates for all age groups.
7- Total marital fertility rate:
The average number of children that would be born to a married woman if she experiences the current fertility pattern throughout her reproductive span.
8- Gross reproduction rate:
The average number of girls that would be born to a woman if she experiences the current fertility pattern throughout her reproductive span (15-49) assuming no mortality.
9- Net reproduction rate:
The number of daughters a newborn will bear during her lifetime assuming fixed age specific fertility and mortality rates. If the NRR is less than one, then the reproductive performance of the population is below replacement level. NRR of one can be achieved only when 60% of eligible couples effectively practice family planning.
10- Child woman ratio:
The number of children 0-4 years of age per 1000 women in the child bearing age (15-49). This ratio is used where birth registration is inadequate. It is estimated through data derived from census.
11- Pregnancy rate:
The ratio of number of pregnancies in a year to married women in the reproductive age (15-49). The number of pregnancies includes all pregnancies whether terminated as live births, still births or abortions or not yet terminated.
12- Abortion rate:
The number of all types of abortions per 1000 women in the reproductive age (15-49).
13- Abortion ratio:
This is calculated by dividing the number of abortions performed during a particular time by the number of live births over the same period of time.
14- Marriage rate:
The number of marriages in the year per 1000 population. It is unsatisfactory as the denominator includes population not eligible to marry.
15- General marriage rate:
The number of marriages within a year per 1000 unmarried persons in the age group 15-49. It is more accurate when computed for women because more men marry at the older ages.
Impact of family planning on Women’s health:
Pregnancy can mean serious problems for many women. It may damage the mother’s health or endanger her life. The risk increases as the mother grows older and after she had 3 or 4 children. By intervening in the reproductive cycle of women, family planning helps them to control the number, interval, and timing of pregnancies and births, thus reducing maternal mortality and morbidity and improving health. Health impact of family planning occurs primarily through:
1- Avoidance of unwanted pregnancies: the essential aim of family planning is to prevent the unwanted pregnancies. An unwanted pregnancy may lead to an induced abortion. Abortion outside the medical setting (criminal abortion) is one of the most dangerous consequences of unwanted pregnancy. There is also evidence of higher incidence of mental disturbances among mothers who have had unwanted pregnancies.
2- Limiting the number of births and proper spacing: repeated pregnancies increase the risk of maternal mortality and morbidity. These risks rise with each pregnancy beyond the third, and increase significantly with each pregnancy beyond the fifth. The incidence of rupture of the uterus and uterine atony increases with parity as does the incidence of toxemia, eclampsia, and placenta previa.
Anemia is a common problem in mothers with many children and the rate of stillbirths tends to increase significantly with high parity. There is a clear association between incidence of cancer cervix with high parity.
Family planning is the only way to limit the size and control the interval between births to improve health of the mother.
3- Timing the births: particularly the first and last in relation to the age of the mother. Short birth interval (≤27 months) are associated with an elevated risk of infant, neonatal and perinatal mortality; low birth weight, small for date and preterm delivery. Women should wait at least 2 years before getting pregnant again.
Generally, mothers face greater risk of dying below the age of 20 and above the age of 35. In many countries, complications of pregnancy and delivery show the same pattern of risk with the highest below 20 and over 35 years.
Impact of family planning on Foetal health:
A number of congenital anomalies e.g Down syndrome, are associated with advanced maternal age. Such congenital anomalies can be avoided by timing of births in relation to maternal age. The quality of population can be improved by avoiding unwanted births and compulsory sterilization of all adults suffering from certain diseases like leprosy, psychosis.
Impact of family planning on Infant and child health:
a- Child mortality:
It is well known that child mortality increases when pregnancies occur in rapid succession. A birth interval of 2-3 years is considered desirable to reduce child mortality.
b- Child growth, development and nutrition:
Birth spacing and family size are important factors in child growth and development. The child is likely to receive his full share of love and care including nutrition he needs when the family size is small and births are properly spaced. Family planning is effective prevention against malnutrition.
c- Infectious diseases:
Children living in a large family have an increased risk of infection especially infectious gastroenteritis and respiratory and skin infections.
d- Intelligence:
Studies have shown lower IQ scores among children in larger families.