In the discussion on differential fertility only one variety at a time has been taken into consideration with a view to explain the differences in fertility among various sub-groups in a population.
It must, however, be recognised that these entire variable are closely interrelated. For example, when the husbands are high educated, they tend to have educated wives.
Higher education levels are related to higher incomes and more gainful occupation leading to higher standards of life.
In a community in which worn are educated, the influence of religious dogma is likely to be rigid, while if the 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 education attainment of wives.
When fertility differentials are studied in relation to various ecological, socio-economic and cultural factors, it is found that, many developed countries, they are narrowing, and the latest truer is towards uniformity.
On the other hand, in a developing count like India, fertility differentials have, in recent times, becom 1 increasingly pronounced. Amos Hawley has identified three phase in the trends in fertility differentials.
In the first phase, various socio-economic classes either had identical fertility rates or the relationship between socio-economic status and fertility was position.
In the next phase, which began with industrialisation and t resulting socio-economic development, it was the highly education urban elite group which first began to show declines in fertility thus showing a wave of fertility differentials.
In the final phase which is in existence now in many Western countries, there appear to be a positive association between socio-economic statuses and fertility.
India is at present in the transitional stage of fertility and, therefore, differentials among various socio-economic classes are becoming increasingly more pronounced.