Recently published data demonstrate that different populations have varying levels of salivary progesterone (P), but researchers are uncertain as to its significance. Among less well-nourished and more stressed populations, P levels are chronically lower than among healthy Western controls. Some reproductive ecologists have suggested that this variability represents different levels of ovarian function, but other demographers counter that women living in such marginal conditions exhibit high fertility and hence must remain fecund. There has been no direct measures of the relationship between interpopulational differences in fecundity (the capacity to conceive) and interpopulational variability in such reproductive steroids that would clearly support either of these assertions. Resolving this dispute is essential before considering either the implications or causes of interpopulaitonal variability in salivary P. This research project by two younger women researchers proposes to examine the following related three hypotheses: 1) there are significant interpopulational differences in chronic levels of P; 2) women in more stressful environments have lower levels of P than women living in better conditions; and 3) these interpopulational differences do not translate into differences in fecundity and fertility. To test these hypotheses, the investigators have chosen for study a traditional Quechua-speaking population in rural Norte de Potosi, Bolivia, who live in dispersed communities and rely almost exclusively upon agriculture and herding for subsistence. They do not attempt to limit the number of births and venereal diseases are not common. Women will be sampled longitudinally for levels of salivary P, and concurrent conceptions will be detected using urinary indicators of human chorionic gonadotropin. Demographic information will also be collected related to fertility determinants. The study is expected to help resolve the outstanding and much-debated issue between demographers and reproductive ecologists described above - specifically, whether recorded physiological indicators of variable ovarian function reflect differences in fecundity and fertility.
