292 DR MATTHEWS DUNCAN ON THE 



Chapter IV. — The Fertility of Fertile Marriages lasting during the whole 



Child-bearing Period of Life. 



This subject may be stated in the form of a question. How many children 

 does a fertile woman produce, living in wedlock from 15 to 45 years of age? The 

 only collection of data known to me, which can throw light on this point, is that 

 published in the "Report to the Council of the Statistical Society of London, from 

 a Committee of its fellows, appointed to make an investigation into the state of 

 the poorer classes in St George's-in-the-East." * In that district there were found 

 80 mothers married at ages varying from 15 to 19, and who had lived in wed- 

 lock at least 31 years. These fertile wives having lived nearly all the child- 

 bearing period of life in wedlock, had borne on an average 9-12 children. 



There are evident sources of inexactness in the above very limited data, 

 which tend to diminish the average fertility ; and it will be as near the truth 

 to state 10 as the average fertility of fertile marriages lasting during the whole 

 child-bearing period of life. 



The conclusions given in further parts of this paper will show that the figure of 

 10 children, for 30 years of child-bearing life, is Dot indicative of each mother 

 having borne a child every third year. The fertility, while it lasts, will be shown 

 to be much intenser than this. The average interval between births of living 

 children is hereafter shown to be 20 months, which gives about 17 years as the 

 average duration of fecundity in a fertile woman living in the married state all 

 the child-bearing period of life. 



In his work on Abortion and Sterility, Dr Whitehead gives no data which I 

 can properly collate with those just given. After stating his belief that the actual 

 duration of the child-bearing period in the female of this climate is about 20 

 years, he adds, that a woman, under favourable circumstances, has in that 

 period 12 children. But as this includes abortions and premature deliveries, 

 which he estimates at 1^ for each individual, the figure 12 has to undergo that 

 reduction for comparison with 10, and the approximation is very close. 



Sadler states as a fact, " that marriages, on the average, are only fruitful for 

 about a third part of the term of possible fecundity. f" But he nowhere, so far 

 as I know, affords any evidence of this statement, and I therefore attach to it no 

 importance. 



* Quarterly Journal of the Statistical Society, August 1848, vol. xi. 

 t Law of Population, vol. ii. p. 276. 



