314 



THE TREND OF THE RACE 



dimensions is simply due to the fact that the greater the age of 

 the mother the greater is the number of previous deliveries, and it 

 follows that if the women married as soon as they were capable 

 of bearing children we should expect, with a rise in the fertility, 

 an increase in these dimensions in the foetuses." {Problems in 

 Eugenics, II, 1 17-18.) 



With advancing age of parents there is in general a higher death 

 rate of children in the first year of life. There is, however, a 

 preliminary descent from the earlier ages due probably to the 

 high death rate of the first born. The statistics studied by 

 Ewart show that the infant mortality falls "until the twenty- 

 fourth year is reached and then slowly rises again," reaching 

 its maximum in mothers of over 40 years of age. This is Indi- 

 cated in the following table: 



Infant Mortality According to Maternal Age 



Age of Mother 



Under 19 



20-24 Inc 



25-29 



30-34 " 



35-39 " 



Over 40 Inc. . . 



No. of Births 



152 

 536 

 396 

 316 



150 

 36 



Deaths in ist Year 



26 

 66 

 66 

 74 

 34 

 12 



Per 1,000 Births 



171 

 132 

 166 

 170 

 220 

 330 



After the initial fall the rise in the infant death rate with in- 

 creasing years of the parents is very striking. Data from New 

 South Wales from 1893 to 1900 dealing with 277,799 confinements 

 show a similar fall to the 20th year of the mother's life, and a 

 gradual rise with later years, the infant mortality of mothers 

 above 40 being over four times as heavy as in mothers of 20. 

 When first births alone are tabulated there is a similar fall until 

 the 20th year is reached, after which there is a rise, as is indi- 

 cated by the following table based on 56,247 first births: 



