Pilot and astronaut offspring: possible G-force effects on human sex ratio.

Ratio of male to female offspring in tactical pilots and astronauts who experienced G forces was compared to that of pilots and non-rated officers who were not exposed to such conditions. In the analysis presented here we found 62 pilots and astronauts exposed to higher G forces had a significantly lower ratio of males to females in their offspring (.40) than did 220 pilots and non-pilots who were not exposed to high G forces. Other studies have also reported a decreased sex ratio in offspring of men exposed to high G forces. Reduction in number of males produced by fathers routinely exposed to comparatively high-G stresses may be related to G-force effects on sperm. This study suggests high-G exposure may affect the reproduction process.