THE CAUSES OF. THE DECLINING BIRTH RATE 145 



states make a serious attempt to compel such registration by law. 

 While physicians and midwives may comply with the regulation 

 for reporting births, there are many children born without attend- 

 ance, and which, therefore, are frequently not registered. More 

 care has been taken recently in compiling data on births with the 

 result that a larger number are reported. The rise in the birth 

 rate of several of our states is not improbably due largely to this 

 cause. Massachusetts has for many years compiled data on 

 births and has passed laws compelling birth registration, but the 

 U. S. Children's Bureau has made a thorough study of a limited 

 district in that state with the following results: "99 births were 

 found to have been registered twice, 10 births were registered 

 which actually occurred outside the limits of the municipality, 

 10 births occurred in another year from that in which they were 

 registered;" 123 births for one reason or another were not regis- 

 tered. The errors, which were considerable, happened to offset 

 each other fairly well since the record showed only 14 fewer births 

 than actually occurred. 



The birth rate is undoubtedly affected by changes in the age of 

 marriage and in the frequency of marriage, but it is evident that 

 neither of these causes can account for more than a small part of 

 the general decline in the birth rate during the past fifty years. 

 Marriage statistics suffer greatly from inaccuracy of data on the 

 age of marriage. As most people do not consider it a matter of 

 much importance to report the true ages of the contracting par- 

 ties, the age of the woman especially is frequently stated to be a 

 few years younger than it really is. 1 Conclusions in regard to 

 the effect of the marriage rate and age of marriage on the birth 

 rate, so far as the United States is concerned, must be regarded as 

 tentative. According to the U. S. Census for 1910, there has been 

 for both sexes a gradual advance since 1890, in the percentage of 

 married persons and in the percentage of married, widowed, and 

 divorced persons combined. "In the age groups 15 to 19 years, 



1 For a discussion of what might be called the coefficient of mendacity for differ- 

 ent ages of Australian brides see Knibbs, The Mathematical Theory of Population, 

 Appendix A, of the Census of Australia for 1911, Vol. i. 



