Natural family planning.
D000328:Adult; D001831:Body Temperature; D002582:Cervix Mucus; D005260:Female; D005298:Fertility; D006801:Humans; D008598:Menstruation; D012252:Natural Family Planning Methods; D009774:Obstetrics / Q000193:education; D010053:Ovary / Q000502:physiology; D010060:Ovulation; D011247:Pregnancy; D011446:Prospective Studies; D012106:Research; D012189:Retrospective Studies; D014944:World Health Organization