Ecology of Breastfeeding: Approaches Toward Improvement of Women’s and Children’s Health VIRGINIA J. VITZTHUM* AND VI ´ CTOR M. AGUAYO Department of Anthropology, University of California, Riverside, California ABSTRACT It is well established that breastfeeding has significant ben- efits for infant health and plays an important role in regulating maternal fecundity. However, many questions remain regarding the mechanisms un- derlying these relationships and the sources of the observed variation among individuals and populations. For example, women of seemingingly compa- rable breastfeeding magnitude and nutritional status display substantial heterogeneity in the duration of postpartum subfecundity. This variation may be related to breastfeeding structure, which in turn is the consequence of variation in ecological conditions. In addition to theoretical questions, it is essential that efforts are directed toward addressing the issues of improving women’s and children’s health. Women have multiple roles and obligations, including a responsibility for their own well-being as well as that of their children. Women also have a right to determine the course of action most appropriate for themselves. Under suitable conditions, breastfeeding is the best choice for the well-being of both the mother and infant; hence, provided with these conditions most women will choose to breastfeed. Working within an ecological perspective, human biologists have an opportunity to bridge the gap between theoretical and practical issues by conducting research that also contributes to the advocacy of women’s and children’s health. Am. J. Hum. Biol. 10:145–149, 1998. © 1998 Wiley-Liss, Inc. INTRODUCTION: EXPLORING HUMAN LACTATION There have been two primary foci in the study of human lactation: the consequences of breastfeeding for infant health and the effects of breastfeeding on maternal fecun- dity. Overwhelming data argue for the pro- tective benefits of breastmilk on infant health, especially in developing countries where breastfeeding is clearly associated with reduced infant mortality and morbid- ity. In the study of maternal fecundity, the relationship between breastfeeding and ovarian function has been so amply demon- strated that the period of postpartum sub- fecundity is often referred to as ‘‘lactational amenorrhea.’’ Although not abandoning additional re- search into these primary linkages between breastfeeding and infant health or maternal fecundity, there is much to be gained by widening the breadth of inquiries. For ex- ample, much of the body of research to date has implicitly assumed that the interaction between breastfeeding behavior and either ovarian function or infant health is essen- tially comparable across populations. The wealth of data now available demonstrates that this is clearly not the case. Rather, these relationships vary among populations in ways not originally anticipated. It is also the case that a great deal of effort has been expended in the precise measurement of outcome variables, such as the timing and patterning of the return of postpartum fe- cundity, but little attention has been given to careful measurement of the causal vari- Contract grant sponsors: the University of California and the National Science Foundation; Contract grant number: (SBR- 9506107 (to V.J.V.). *Correspondence to: V.J. Vitzthum, Department of Anthropol- ogy, University of California, Riverside, CA 92521-0418. E-mail: vitzthum@ucrac1.ucr.edu Received 29 May 1997; Accepted 3 June 1997 AMERICAN JOURNAL OF HUMAN BIOLOGY 10:145–149 (1998) © 1998 Wiley-Liss, Inc. PROD #729