Relevance of menarche, menopause and other bio-events to fertility. fertility patterns and differentials.
Fecundity and Fertility.
Fecundity refers to the capacity of man, a women or a couple to participate in reproduction- i.e. the capacity to produce a live child. Fertility on the other hand refers to the actual reproductive performance-whether applied to an individual or a group. While there is no direct measurement of fecundity,fertility can be studied from the statistics of birth. Fecundity also refers to maximum fertility levels that can be attained.
While a man or a women or a couple who has given birth to at least one live child is considered fertile,one who had not had a single child is sterile. Sterility can be natural /involuntary or artificial/voluntary.
A women becomes biologically fecund with the onset of menstruation. The onset of menstruation is called Menarche. Her capacity to bear children comes to an end with the onset of menopause,when menstruation ceases. Women can bear children from the age of 15 to 44 years. The reproductive span of men is not actually defined but is considered more than women.
Theoretical maximum fertility.
Theoretically,during the physiologically limited child bearing period,a women would get 37 children,if she give birth to one children every 10 months over a period of 31 years.
The interval between menarche and the attainment of full biological maturity to bear children is therefore called the period of adolescent sterility. A womens capacity to wear children reaches the highest level at 20 to 25 years,after which it starts declining first slowly and then after the age of 38 quite rapidly and reaches zero at 50.
Post partum sterility.
After the birth of a child,the women is generally sterile for some period, as the menstrual cycle is not resumed.,or if it is reestablished the earlier cycles are unovulatory. This post partum period in which menstruation is not resumed is known as the post partum amenorrhea period. During this period the possibility of conception is very rare and hence this period of temporary sterility is known as post partum sterility.
Reproductive wastage in terms of abortions and stillbirths also act as physiological factors affecting fertility.
Fertility patterns and differentials :
It has been observed that the levels and patterns of fertility vary considerably in various sub groups of the same population. These sub groups may be based on residence , whether urban or rural, social and caste,race etc. a study of differential fertility is useful in identifying the factors which determine the fertility levels among various sub groups.
Differential fertility can be understood as a result of following factors.
a)Regional differences in fertility-there is a great deal of variation in fertility among various states and union territory.
b)rural urban residence and fertility-it was found that the fertility of those residing in cities was lower than that of rural residence and these differentials were more or less stable. However when national birth rate declined these fertility differentials widened in a more pronounced manner among urban upper classes than among others. Rural urban differences narrowed down again when birth rates rose after the second world war.
a)educational attainment and fertility-the educational attainment of couples has a very strong bearing on the number of children born. The higher the educational level the lower was the family size.
b)economic status and fertility-general studies in the past have highlighted the inverse relationship between the economic status of family and fertility. this traditional relationship is now undergoing substantial changes as far as the developed countries are concerned.
c)occupation of husband and fertility.
Occupation of husband is used as the indicator of social economic status,and differential fertility is studied according to the occupation of the husband. It was generally observed that the wives of those engaged in professional jobs had the lowest fertility.
d)employment of wife and fertility.
The gainfully employed women have a smaller number of children than those who are not employed.
e)religion,caste,race and fertility.
The injunctions laid down in various religion indicate the importance of high fertility.
Christian-be fruitful multiply and replenish the earth.
Islam-marry a women who holds her husband extremely dear and who is richly fruitful.
Hinduism-make the bride the mother of good and fortunate child bless her to get 10 children and make the husband the eleventh one.
It may however be noted that all these religions have their roots in distant past when mortality rate was high.
It was observed in india that muslims have a higher fertility rate than hindus and christian.
It was observed that upper caste hindu had on an average 3.8 live births while lower caste hindus have 4.1 births.
In the us the negroes show more fertility than the white ones.
Inter-relationship between socioeconomic variables affecting fertility.
When the husbands are highly educated, they tend to have educated wives. Higher educational levels are related to higher incomes and more gainful occupations leading to higher standards of life. In a community in which women are educated the influence of religious dogma is likely to be less rigid, while if community has a high proportion of illiterate women,religious influences tend to be strong and affect fertility. Age at marriage is also closely associated with the educational attainment of wives.