Terms in reproductive and perinatal epidemiology: I. Reproductive terms.

Accepted for publication 31 August 2004 . . . . . . . . . . . . . . . . . . . . . . . T he terms included in the glossary have widely diverse origins, ranging from endocrinology and reproductive biology to sociology and demography to obstetrics and paediatrics. Perhaps because of these disparate origins, definitions are not always consistent. Frank differences in definitions of common variables can lead to inconsistencies among research studies. 2 Even more confusing is that the definitions may seem contradictory. For example, a couple can be defined as infertile and then fertile, and then infertile again. While a glossary cannot resolve all these problems, it provides a point of reference for understanding these problems. When conflicting definitions are in use, we rely on the ICD-10 definition if available. Part one focuses on processes before birth, while part two emphasises those after birth. Terms are generally alphabetical within each part, although a few terms are grouped for clarity.