Fertility Measures and Determinants

As you know lower mortality rates in a community often indicate better nutritional status. How would you interpret lower fertility rates in a community? Do they indicate a good or bad state of nutrition? In India we have less food and high fertility rates. In other words nutritional status does not seem to influence fertility rates. Let us now learn about the various fertility rates which are computed from the point of public health significance. 

Crude Birth Rate (CBR) 

The number of live births per 1000 estimated mid-year population of a community in a given calendar year. It can be calculated by using the following formula.

                      Number of live births  in a year in a given area

Birth Rate = -------------------------------------------------------------------------x  1000
                        Estimated mid-year population  

It is one of the major determinants of population growth in any country. 

Birth rates are observed to be higher in the developing countries when compared to the developed world. For example, the birth rate in India is 29.9 when compared to 13 in Sweden, 14 in UK and 16 in USA. The birth rates are however, declining gradually in the developing countries. In India, it has declined from 43 in 1960 to the present figure of 29.9. 

The causes of high birth rate are : 

• Early puberty : Indian girl's attain puberty early, i.e. between 12 and 14 years. 
• Early marriages 
• Universality of marriage : Every one gets married irrespective of one's economic security or mental maturity. 
• Poverty and low standard of living with its implications for child survival is associated with high birth rates and vice-versa. 
• Low literacy rates especially the low female literacy level is associated with high birth rate. 
• Value of children, acts as a pronatalist  force (high fertility) 
• Low prevalence of family planning and adoption: The use of family planning methods to adopt a small family norm is yet to make any impact on  the population  explosion. 

General Fertility Rate (GFR) 

This is a measure.of fertility. It is defined as the number of' live births per 1000 women in the reproductive age group (15-49 years) in a given year

                            Number of  live births in an area during the year 

GFR  =       ----------------------------------------------------------------------------------  x 1000

               Mid-year female population in the age group of  15-49 years in
                                    the same area during the same year 

GFR is considered to be a better indicator of fertility than the crude birth rate as only the women in child bearing ages are included in the denominator. However, you may note that all the women included in the denominator need not bear children. 

A more precise measure of fertility  is available which is known as Age specific fertility rate where the number of live births are computed per 1000 women in a specific age group. This gives a better picture of  fertility pattern and serves as a sensitive indicator of  the achievements of the family planning programme. 

The General Fertility Rate in 1987 in India was  134. It was higher in rural India (142) when compared to urban areas (109). It may interest you to know that GFR is lowest in Kerala (77) and very high in Rajasthan (157) and Uttar Pradesh (170). The figure for age specific fertility rate indicates that the peak age of  fertility in women is between 20-24 years. The fertility remains almost equally high in the age group of 25-29 years. There are urban-rural differences in the fertility rates and fertility is high in rural India. 

Total Fertility Rates 

Total Fertility Rate gives the average number of children a woman can bear if she passes through her entire reproductive  life. 

TFR is computed by summing up the age specific fertility  rates per woman. 

This fertility indicator is independent of the age and sex composition of the population. It indicates the approximate  magnitude of completed family size. 

The TFR of India was 4.1 in 1987. TFR was high (4.4) in rural areas compared to the urban region (3.2). It is again very high in Rajasthan (4.8) and Uttar Pradesh (5.5) when compared to Kerala (2.2). At the national level a declining trend of TFR has been noticed. 

Net Reproduction Rate (NRR) 

NRR is the average number of live female children that would be born  to a woman, with the existing fertility and mortality pattern in the age group of 15-49 years. 

NRR indicates the number of live female children that are going to replace a mother within the reproductive period. 

NRR in India is estimated to be 1.61 (1980-85)  and is found  lo be declining.