What are the Biological Limits and Social Norms of Fertility?

Though the birth of a child is basically a biological phenomenon, child-bearing in any society occurs in a social set-up and is, therefore, affected by the social structure as well as societal customs, values and norms related to various aspects of child- bearing.

For instance, an understanding of social mores and customs concerning the sexual behaviour of men and women is relevant in the study of fertility, for conception results from the sexual act.

As value systems usually demand that reproduction should take place within wedlock, the social norms and customs regarding marriage in any society also affect societal reproduction.

The point to note is that, within the physiological limits set for human reproduction by Nature, a number of social, cultural and psychological factors influence the levels of, and differentials in, fertility in any society.

In the study of fertility it is necessary, therefore, to understand the biological aspects of fertility as well as the effects of various societal norms and customs related to the processes involved in child- bearing.

Reproductive Span

The biological limits imposed on child- bearing by such factors as age and sex can be easily recognised. Only women can conceive and give birth to children, and that, too, within certain age limits.

A women becomes biologically fecund (capable of bearing a child) with the onset of menstruation. Her capacity to bear children comes to an end with the onset of menopause, that is, when menstruation ceases.

In a 1938 study of 142 countries, Raymond Pearl found that menarche, that is, the onset of the first menstrual period, occurred generally when a girl was between 13 and 17 years.

Recent research, however, indicates that the age at which menarche occurs is not constant, and varies according to time and place.

It has been observed that during the last one hundred years, the menstrual age of European girls has gone down and has at present settled at an average of 13 years.

Various environmental changes, which include mainly the changes in nutritional standards and some genetically factors, appear to have been responsible for this decline in the average age at menarche in Europe.

In a survey conducted in 1956, Kumudini Dandekar observed that the average menarcheal age in rural India was 13.8 years. In his study of 142 countries, Raymond Pearl had found that the cessation of fecundity in females occurred at an average age of 46, the range being 44 years to 49 years.

On the other hand, Kamat and Kamat observed that the mean menopausal age for Indian women was 42.2 years. According to Kumudini Dandekar’s findings, nearly 83 per cent of the women in rural India experienced menopause before reaching the age of 50.

On the basis of research evidence, it may be concluded that women can bear children from the age of 15 to 44 years or 49 years. The reproductive span or the child bearing period of a woman, on an average, is between 30 and 35 years.

The reproductive span of men is not well defined, nor is it easily identifiable, though it is generally found to be considerably longer than that of women.

It is to be noted, however, that fecundity of females is not uniform throughout this reproductive span of 30 or 35 years. The woman’s age is an important factor when her reproductive capacity is considered. Female fecundity is at a low level during the early stages of puberty.

A certain degree of adolescent sterility (that is, sterility among the adolescent age group) or sub-fertility is observed for girls between the ages of 13 years and 18 or 19 years.

Adolescent sterility or sub-fertility occurs because regular ovulatory cycles are not generally firmly established for the first two or three years after the onset of menstruation.

The interval between menarche and the attainment of full biological maturity to bear children is, therefore, called the period of adolescent sterility.

A woman’s capacity to bear 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 level at about 50 years.