title: A trial of the ovulation method of family planning in Tonga.
mesh_terms: D000293:Adolescent; D000328:Adult; D002582:Cervix Mucus / Q000378:metabolism* / Q000502:physiology; D005193:Family Planning Services; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008722:Methods; D008875:Middle Aged; D010060:Ovulation; D010507:Periodicity; D011114:Polynesia; D011203:Poverty; D013997:Time Factors; D014626:Vaginal Smears