Artificial insemination with frozen semen. Sex ratio at birth

The purpose of this study was to find out if cryostorage of human semen affects the sex ratio of births resulting from artificial insemination (AI). A survey of the available literature over the last 10-15 years was undertaken. The sex ratio of 3950 births after AI with frozen semen was compared to that of 3086 births resulting from AI with fresh semen and to the total number of births in Iceland during the 10 year period 1972 to 1981, 44.623 births. The normal predominance slightly decreased in births resulting from AI, both with fresh and frozen semen, 50.4% for AI with fresh semen and 49.8% with frozen semen. The difference between the two types of AI in sex ratio is not significant statistically but the two types of AI combined give a probably significant reduction of the sex ratio (P less than 0.05), compared to the general population. It is concluded that cryostorage of semen has not been found to affect the sex ratio at birth but the practice of AI during the last decade might in some way cause a slight reduction of the secondary sex ratio.