Vaginal bleeding patterns among rural highland Bolivian women: relationship to fecundity and fetal loss.

Among the most common reasons given for discontinued use of some contraceptive methods is a disturbance in the menstrual cycle, particularly changes in vaginal bleeding. Work to date suggests marked populational variation in menses duration, but few data have been collected from South America. This longitudinal study of non-contracepting Aymara women (n = 189 providing 837 non-truncated bleeding episodes) identified conceptions and fetal loss via urine tests for human chorionic gonadotropin and classified episodes accordingly to test the hypotheses that (a) vaginal bleeding patterns differ between lactating and non-lactating women, (b) duration of vaginal bleeding accompanying fetal loss differs from that of menstruation, (c) menses preceding a conception are longer than those not followed by a conception. Compared to published values, mean menses duration (3.5 days) in these women was relatively short. Menses duration was not significantly correlated with current age, age at menarche or first birth, parity, time postpartum, or menstrual segment length. Mean menses duration (not preceding a conception) was comparable for lactating and non-lactating women. Mean duration of fetal loss bleeding did not differ from that of menses. Pre-conception episodes were significantly longer than those not followed by conception. Thus, because the rate of conceptions was twice as great among lactating than non-lactating women, the mean duration of all menses (irrespective of conception) was significantly longer in lactating women. Bolivian, and perhaps other South American, women may be particularly disinclined to accept contraceptives (e.g., intrauterine devices) that modify an otherwise relatively brief menses duration. Therefore, a wide variety of contraceptive choices accompanied by population-specific informed counseling is essential. In addition, these findings suggest that studies of fecundability limited to non-lactating women may be biased toward those of relatively lower fecundity and that menses duration may be predictive of risk for some cancers.