Pregnancy Compensation Hypothesis (IMAGE) Arizona State University Caption The Pregnancy Compensation Hypothesis suggests that evolution shaped men's and women's immune systems differently. It also suggests that in modern, industrialized populations, the reduced amount of time women spend pregnant and lactating, and other environmental effects on hormone levels, explains sexual differences in the risk for autoimmune diseases and certain cancers. Credit Jacob Sahertian/ASU VisLab Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.