EVALUATION OF REPRODUCTIVE FUNCTION IN TURKANA WOMEN WITH ENZYME IMMUNOASSAYS OF URINARY HORMONES IN THE FIELD

The frequently reported observation that nomadic populations have lowe r fertility than their settled counterparts is often attributed to wha t are perceived as harsh, stressful conditions under which the nomads live. But the consequences of the hypothesized stresses for the reprod uctive biology or demography of these populations have been documented only a little. Traditionally, the Turkana of northwest Kenya are noma dic herders, but increasing numbers have settled on agricultural devel opment schemes. We used an array of hormonal assays along with anthrop ometric indexes of nutritional status and interviews covering reproduc tive history, recent menstruation, diet, and health to compare reprodu ctive function in nomadic and settled Turkana women. First morning uri ne samples were collected for three consecutive days during a series o f surveys, Human choriogonadotropin (hCG; a marker for pregnancy), lut einizing hormone (LH; an indicator of ovulation), and pregnanediol glu curonide (PdG; an indicator of postovulatory luteal function) were ass essed in the field with commercially available dipstick enzyme immunoa ssays. These assays along with the interview data allowed us to determ ine the reproductive status (e.g., pregnant or cycling, and if cy clin g, which phase of the ovarian cycle) of 166 nomadic and 194 settled Tu rkana women, The cross-sectional classifications allowed inferences of conception rates and normality of ovarian function, Follow-up surveys provided rates of pregnancy loss. Compared with the settled women, th e nomadic women exhibited lower pregnancy rates and cycling nomadic wo men were less likely to show evidence of ovulation or luteal function. These results suggest that reproductive function of the nomadic women is diminished relative to the settled women. However, the settled wom en experienced a much higher rate of pregnancy loss, which may mean th at their effective fecundability is in fact lower than that of the nom adic women. This study is the first to apply such a wide range of horm onal assays in the field. It demonstrates that field-based assays are feasible and robust and can play an important role in egidemiological and biodemographic studies, even in remote locations under conditions that would ordinarily be considered incompatible with on-site laborato ry analysis.