Matthews Duncan compiled the following table relating to 504 absolutely sterile women met with in his practice:

Age at Marriage.Number of Years Married.
Less than 3.4 to 8.9 to 13.14 to 18.19 to 23.24 to 28.29.Totals.
15 to 19121915472160
20 to 2470663724139 219
25 to 2947512088 134
30 to 3426208 1 59
35 to 396134 23
40 to 4563 9
Totals167172844029111504

Ansell bases upon the observations made by him in the case of 152 sterile women the conclusion that there is no longer any chance of the occurrence of pregnancy if a woman is:

More than 48 years old, and has had no child for2 years
More than 47 years old, and has had no child for3 years
More than 46 years old, and has had no child for4 years
More than 45 years old, and has had no child for6 years
More than 44 years old, and has had no child for8 years
Less than 44 years old, and has had no child for10 years

If we take into account also cases of acquired sterility, the proportion of barren to fruitful marriages becomes even more unfavourable, and the proportion increases enormously if, with Grünewaldt, we number among the barren women those who fail to continue child-bearing up to the normal climacteric period. Grünewaldt, dealing with about 1500 women suffering from affections of the reproductive organs, excluded all those who were either virgins or widows, and also all those who at the time of the observed barrenness were over 35 years of age; this left more than 900 women suffering from affections of the reproductive organs, all of whom were sexually mature, and were living in marital intercourse; of these, nearly 500 were barren, 300 being instances of acquired sterility, and 190 instances of congenital sterility. Thus, according to this observer, disease of the reproductive organs in women led in more than 50% of the cases to disturbance of the reproductive capacity; about one in every three women, previously competent to bear children, became barren when affected with disease of the reproductive organs; and among every five gynecological patients of the condition already specified as regards age and sexual intercourse, one proves congenitally sterile.

It must not, however, be forgotten, that sooner or later after marriage artificial sterility tends to come into being, its early or late appearance depending upon the degree of civilization and upon the national and economical conditions of the people and the individuals concerned. This fact must not be left out of the account.

The manner in which, in the human species, fertilization is effected, is still far from clear in all its details; hence it is easy to understand, that the etiology of sterility remains in many respects obscure. It is impossible in every case to find a definite cause. Whereas, on the one hand, notwithstanding the existence of apparently insuperable obstacles, impregnation may nevertheless be effected; so, on the other hand, sterility may exist in cases in which all the circumstances appear favourable to the occurrence of conception. Hence a classification of the different varieties of sterility from the etiological standpoint, is a very difficult task, and the conclusions thus obtained are often vitiated.

Although it cannot be denied that mechanical causes are competent to lead to sterility in women, Sims, in his advocacy of the mechanical doctrine of sterility, widely overshoots the mark. His authority, however, has led to a general acceptance of this doctrine, which is by no means justified by facts. The theory of mechanical obstruction, according to which sterility in women depends upon mechanical obstacles to the passage of the spermatozoa towards the ovaries, is from time to time strikingly illustrated by cases coming under our notice—cases the nature of which can hardly be overlooked; but it is quite wrong to suppose that this causation accounts for the majority of instances of sterility in women, and strict limitations should be placed upon the employment of surgical measures based upon this mechanical theory of sterility.

The mechanical view has been counterposed by Von Grünewaldt with a doctrine in which especial stress is laid upon obstacles to utero-gestation, sterility being regarded as a functional disorder brought about by affections of the female reproductive organs rendering the uterus unfit for the incubation of the ovum. It cannot be denied that the elucidation of this casual influence was a valuable contribution to the theory of sterility, and it is unquestionable that many morbid conditions of the uterus exist capable of giving rise to sterility in this manner; but we must avoid the error of regarding this doctrine as a full explanation of the cause of sterility.

If, however, both of these theories of sterility are insufficient, we cannot regard a third theory, that of Matthews Duncan, as filling the gaps in our knowledge. It would be most unfortunate if this author were right in maintaining that all our knowledge of the causes of sterility is to be summed up in the phrase “deficient reproductive energy;” we cannot agree with Duncan in his belief that “Sterility is an imperfection devoid of all perceptible, measurable characteristics;” nor can we follow him when he maintains that local causes, whether they are such as hinder conception, or such as hinder utero-gestation, have a very limited sphere of activity. Matthews Duncan adopts an incomprehensible standpoint when he regards sterility as dependent upon a law of nature, as a condition which may affect distinct classes or an entire population.