This book stems from the "Textbook of Perinatal Epidemiology" and was conceived to satisfy the rising need for epidemiology-oriented clinicians. This book discusses methodological issues in perinatal epidemiology in a straightforward accessible manner. It gives a clear and comprehensive set of tools for practical research, and understanding perinatal epidemiology. This is an essential manual for the clinician for research in OB/Gyn. This book focuses on definitions, measures of disease frequency, prevalence and incidence of disease, sensitivity and specificity of studies, including examples from the perinatal world. It also discusses study design: observational or experimental, case controlled, randomized etc.