Change, change, change: hormonal actions depend on changes in blood levels.

The main hypothesis outlined in this communication is that changes in hormonal levels are of utmost importance in the female reproductive system physiology. Hormone measurements must be assessed in the context of time and change. We hypothesize that changes in hormone concentrations carry significant biological messages, much more than a given level at a given time point and if proved, this theory could give rise to better approaches to treatment, and risk assessment.