Many wrongly believe that reproductive cycles are very similar among human females. In actuality, there are considerable variations among individuals and within the reproductive life of any given female. ''Normal'' reproductive cycles cover a wide range of examples, and the likelihood of successful monthly egg release and ensuing pregnancy can be modified by many factors. In this book, the variability of human fertility is examined by looking first at the physiological processes regulating reproduction. Interpopulation variation in normal ovarian function is then discussed, covering the importance of factors such as age and disease in the modification of ovarian function. The final part of this text covers issues of metabolic effects on reproduction. Researchers will welcome this definitive compilation of observations on fertility.