THE CAUSES OF THE DECLINING BIRTH RATE 165 
has not been allowed to do so. We cannot, therefore, for several 
reasons attribute to reduced infant mortality a large part of the 
decline of the birth rate, although this has doubtless been one 
factor. 
The influence of venereal diseases upon the decline of the 
birth rate, although undoubtedly considerable, is difficult to 
estimate. No reliable data exists as to the proportion of the 
population affected by these diseases, although their prevalence 
is a matter of common knowledge.!_ That the two most common 
venereal maladies are potent causes of sterility has long been 
recognized. Gonorrhcea, which, according to several medical 
authorities, has at one time or another affected more than 50 per 
cent of the adult male population, is responsible for a large 
amount of sterility, the extent of which the medical profession has 
only recently come to appreciate. Through obstructing the vas 
deferens or epididymis, as well as in other ways, gonorrhcea is a 
not infrequent cause of sterility in the male sex. Furbringer 
attributes one-third of all sterile marriages to this cause. Kohern 
found in 96 sterile marriages 30 per cent due to the absence of 
sperms in the seminal fluid of the husband. The greatest damage 
is done, however, by the transfer of the infection to wives, which 
often takes place even after the disease has apparently ceased in 
the husband. Gonococcus infection, according to the moderate 
estimate of Prinzing, causes 13 per cent of sterile marriages. 
Noggerath places the percentage of sterility in woman due to this 
cause as high as 50, and Neisser believes that 45 per cent of sterile 
marriages are due to gonorrhoea of one or the other sex. This dis- 
ease is a frequent cause of failure to produce more children after 
the birth of the first child owing to the rapid extension of the in- 
fection after childbirth. The extent to which complete or partial 
sterility is due directly or indirectly to this cause must be very 
considerable, although it is not capable of precise measurement. 
1 The best index of the prevalence of venereal diseases in the U. S. is afforded 
by the examination of recruits in the late war. According to the Report of the 
Surgeon General for 1919, 5.6 per cent were found to be infected at the time of the 
draft. This figure includes negroes among whom venereal infections were about 
seven times as frequent as among the whites. 
