Research in Causes of Variations in Fertility

HE SIZE of any given family, which in the aggregate influences the fertility rate of the socio-economic group to which that family belongs, is determined by a number of intimately related factors: social, economic, psychological, and biological. It is difficult to consider the role of any single group of these factors without at the same time considering its relationship with all the others. The biological or factors which may cause variations in fertility may be classified into two groups: (a) involuntary causes-those which are due to differences in physiological activity or intercurrent pathology and which happen without reference to any effort on the part of individual couples to control their fertility, and (b) voluntary causesthose which are the direct result of conscious efforts to control fertility. In the strictest sense, voluntary control of fertility is of sociological rather than of medical concern, but insofar as voluntary control affects the public health, it also becomes a medical problem. Both groups of factors may be present at the same time, but for convenience they will be discussed separately. Present knowledge concerning the involuntary causes of variations in fertility relates to those factors which lessen fertility or produce sterility. They are of two types: (i) those which interfere with the possibility of the fertilization of an ovum, and (2) those which interfere with the wife's ability to bear a live child. It is important to emphasize the fact that absolute sterility is a rare phenomenon. Meaker found that only 30 percent of the cases coming to him for the medical treatment of sterility could be classified as absolutely sterile. Fertility is not an all or none proposition. Reynolds and Macomber,' in experiments with rats, found that the fertility of a mating was the product of the fertility of the individual partners. All individual fertilities, as tested by the trial and error method, were expressed in percentages and it was found that the average individual fertility of males and females was the same, approximately o.8. Thus, the average mating fertility was the product of o.8 and o.8 or o.64. Approximately the same mating fertility resulted from mating two animals with individual ratings of o.9 and 0.7 or of I.o and o.65. From a long series of experimental matings the authors determined that when the

Fertility · Population · Sociology · Assisted Reproductive Technology and Twin Pregnancy · Demography · Insurance, Mortality, Demography, Risk Management · Psychology · Reproductive Health and Technologies

• Paperback Abortion

  Kate Gleeson•Australian Feminist Studies•2011

  Add to list

• Time of Ovulation in Women

  Frank H Hankins, Carl G Hartman•American Sociological Review•1937

  Add to list