Despite the low contraceptive prevalence among the Mayan population of Guatemala, past research has found interest in natural methods. A calendar rhythm method with a simple blanket rule would appear to be preferable to more complicated methods. Under a blanket rule, the number of days of abstinence is predetermined and all couples are instructed to abstain during the same interval of the menstrual cycle. However, regular menstrual cycles may be key to successful practice of a calendar method. A database of 880 cycles of 301 women of the Guatemalan highlands was analyzed to determine the length and regularity of menstrual cycles in this population.
PIP: This article reports on the irregular cycle incidence among Mayan women who reported regular cycles. Data from a research study of a blanket 9-19 calendar rhythm method were analyzed to assess the regularity of cycles among the subjects. The necklace method tested in this study is a natural family planning method utilizing the "blanket rule". Sexual abstinence starts on day 9 of the menstrual cycle until day 19. A necklace with 30 beads is used as a mnemonic device. Findings showed that the menstrual cycles of highland Guatemalan women may not be very regular, indicating that women interested in practicing a method with a standard rule of abstinence could be taking risks of getting pregnant. Pregnancies occurred during the course of the study, suggesting cycles of irregularity. Given these results, programs that teach fertility awareness methods should help Mayan women monitor the length of their cycles more closely.