Sex ratio in a sample of human fetuses in Denmark, 1962-1973

The sex ratio was determined in 791 fetuses from pregnant women in the Copenhagen area 1962-1973. All the mothers were sterilized in connection with an induced abortion. Eighty percent of the fetuses had a crown-rump length between 50 mm and 150 mm corresponding to postmenstrual age of 11-19 weeks. The sex ratio was 138. There was no association between length and sex ratio. The difference between this sex ratio and that for live births in Denmark 1962-1973 (105-9) is substantial.