The generous use of graphs and pictures to display concepts that may be difficult for nonbiologists greatly improves the accessibility of the in-formation. Short chapters also aid accessibility for students with limited time and sometimes short attention spans. Two chapters in ''Foundations'' address fertility. The first briefly reviews biologic and epidemiologic evidence sur-rounding the timing of intercourse, ovulation, and preg-nancy. The second chapter focuses on population growth and birth control methods. Historical anecdotes are pre-sented, offset from the rest of the text in gray boxes, that tell interesting stories. For example, ''A Short History of Pregnancy Tests'' describes how Egyptian women were ad-vised to urinate on barley and wheat seeds as a means to assess maternity status.

The inclusion of such humorous but informative anecdotes helps to promote the notion that epi-demiologists are, indeed, interesting people. Also included in ''Foundations'' are chapters on infection, genetics, and—surprisingly—eugenics. (The inclusion of the latter provides excellent fodder for class discussions!) An entire chapter is devoted to the discussion of hetero-geneity of risk.

Although this topic, along with recurrence risk, can easily take up several chapters in a more advanced textbook, limiting the coverage to a chapter in this introduc-tory text is entirely appropriate. In similar texts, the topic usually receives cursory mention and it is frequently ignored altogether in the literature.

Through the use of easy-to-understand diagrams and examples, Dr. Wilcox illustrates the underlying variability in baseline risk in the population and how that risk is revised once we have observed at least 1 prior outcome. He also notes the importance of not adjusting for the prior occurrence of a condition when conducting a study of recurrence where the hypothesis is etiologic in nature. Such adjustments would likely lead to significant biases because both the prior and current disease events are likely to be on the same causal pathway.

Given the importance of these issues to correct interpretation of study results, the attention devoted to this topic is applauded. The last chapter in Part I suggests possible study designs for reproductive outcomes and addresses the major chal-lenges faced by reproductive epidemiologists. This may be one of the most useful chapters in the textbook for working epidemiologists. Deceptively short, this chapter contains an immense amount of practical information of the type that begs for regular reading. Students of reproductive epidemi-ology should commit it to memory. Part II of the textbook is entitled ''Outcomes'' and in-cludes a wide variety of topics of interest to reproductive epidemiologists.

The first chapter in this section, ''Fertility and Fecundability,'' addresses an issue that arises frequently in epidemiologic outcomes in general—the dichotomization of an outcome that is, in fact, continuous, along with other methodological problems. The placement of this chapter at the start of this section is effective. Common methodolog-ical issues that arise in this specialty (and others) can be found in the study of fertility, including problems of out-come definition, case identification (cases may themselves be unaware of their status or may opt not to self-identify), misclassification of case/control status, identification of an appropriate control group, lack of generalizability, inappro-priate sample collection, or handling. This chapter covers those that are most critical.

The ''Outcomes'' section of the textbook also includes 2 chapters on pregnancy loss. Few, if any, epidemiologists understand the issues surrounding the study of early preg-nancy loss and miscarriage better than Dr. Wilcox and, as expected, coverage of these 2 topics is admirable. A discus-sion of the problems encountered when analyzing data on miscarriage risk includes strategies for avoiding the usual pit-falls. Also included are the required chapters on preterm de-livery, birth weight and fetal growth, infant and maternal mortality, birth defects, and preeclampsia.

Each of these chap-ters is well planned, includes recent literature on the subject, and uses graphs and data to excellent effect. Several chapters are included on topics not regularly included in textbooks on reproductive epidemiology but that seem especially pertinent given current trends. These topics include multiple births, sex ratio, and fetal exposures and adult disease. I fortuitously received this book midway through the course I was teaching on reproductive epidemiology and promptly switched textbooks and revised all of my slides