OK, so there was a *small* study published last year (article about the study
HERE) that found that muscle mass gain was significantly smaller in women following a strength-training program while using hormonal birth control than a control group. (Note: there weren't performance differences between the groups, just differences in muscle mass.)
I'm not aware of any research done to follow this up, but as a completely unscientific poll: anyone notice differences in their muscle gains on and off hormonal birth control pills?