ABSTRACT
Pregnancy is arguably the most important factor i n defining an ind iv id ual's reproductive success. From a demographic standpoint, pregnancy represents a crude dichotomy: the production of a live b i r th or intrauter ine death w i t h no live bir th. But as a complicated physiological process, pregnancy is never as simple as the successful or unsuccessful production of a live bir th. Indeed, pregnancy and the perinatal period may represent one of the defining moments for natural selection. Adequate fetal growth influences short-term outcomes such as postnatal growth, development, and survival. Over the long term, intrauterine growth predicts risk for adult onset chronic diseases (Barker et al. 1993), can impact adult repro ductive function i n females (Kline et al. 1989), and plays a crucial role i n overall survival rates (Kramer 1987). In turn, adequately meeting the metabolic demands of gestation and the spacing of pregnancies have short-and longer-term consequences on the mother's health and fitness.
