180 STUDIES ON PATHOLOGIC OVA. 



PRIMARY SEX-RATIO. 



The sex-ratio of fertilized ova can not be determined directly; however, there 

 is an indirect method of solving the problem of the original sex-ratio by means of 

 computing the mortality of cyemata. 1 In case the sex-ratio of fetuses dying in 

 uie.ro is equal to the secondary sex-ratio, then only will the latter and the primary 

 sex-ratio be equal. If the number of males and females that were aborted or 

 still-born were absolutely the same, then the primary would be lower than the 

 secondary sex-ratio. If, however, the sex-ratio of mortality during pregnancy 

 exceeds the sex-ratio of the living-born, then the primary sex-ratio must of neces- 

 sity be greater than the secondary, and indeed increasingly so as the total intra- 

 uterine mortality becomes relatively greater. It is necessary, therefore, to consider 

 two factors in order to deduce the primary sex-ratio from the secondary: (1) The 

 sex-incidence in abortions, and (2) the relative frequency of abortions. Both of 

 these factors i. e., the sex-ratio and the relative rate of mortality differ in the 

 various periods of pregnancy, thus complicating the calculation of the primary 

 sex-ratio. I have endeavored to gather from the literature estimates and statistics 

 concerning the intrauterine mortality, beginning with the relative frequency of 

 still-births and abortions. 



The relative number of still-births differs to some extent according to the 

 various authors. This is in part explained by the fact that the statistics are taken 

 from different countries and at various times. Von Winckel (1903) reported that 

 in Berlin, during a period of 70 to 80 years, the number of still-born males varied 

 from 3.2 to 7 per cent of all births, that of females from 2.5 to 5.5 per cent. Rauber 

 states that in Germany the still-births amount on an average to 4 per cent of 

 1,800,000 annual births. According to Carlberg (1886), the proportion of still- 

 births to the total number of births in Livland lies between 2.58 and 2.90 per 

 cent, while the percentage for western Europe lies between 4 and 4.5. According 

 to Prinzing (1907), from 1891 to 1900 the following proportions of still-births 

 occurred in every 100 births: Austria 2.9, Switzerland 3.6, Italy 3.9, Holland 4.3, 

 Belgium 4.5, France 4.6. These figures are somewhat increased when expressed 

 in percentage of the living-born. Computing from Auerbach's (1912) statistics 

 of over 100,000 births in Budapest, the still-births amounted to 3.3 per cent of the 

 living-born. Bucura (1905) found that among 40,169 births in the Clinic Chrobak 

 in Vienna, 5.8 per cent were still-born; Le Maire (1906) found 5.7 per cent among 

 40,339 births in Copenhagen. Both of these figures are too high, inasmuch as 

 these authors did not use the term still-born in the usual sense, a small number of 

 abortions being included. Nichols (1907) quotes the following figures from regis- 

 tries of vital statistics: 3.6 per cent of total births of whites in the United States 

 are still-births, and among the negro births of the District of Columbia 13.8 per 

 cent are still-born. The percentage of still-births in Japan is 8, according to the 

 same source. These figures from Nichols also include abortions, but inasmuch as 

 these are not nearly so regularly reported as miscarriages in the last few months 

 of pregnancy, they do not considerably increase the percentages. 



1 I use the term cyemata as a collective name for fertilized ova, embryos and fetuses. (See Meyer, 1919.) 



