Rhythm: systematized chance-taking.
D000328:Adult; D001831:Body Temperature; D002410:Catholicism; D002582:Cervix Mucus; D003075:Coitus; D003267:Contraception / Q000379:methods*; D005193:Family Planning Services; D005260:Female; D005306:Fertilization; D006801:Humans; D008297:Male; D008598:Menstruation; D010060:Ovulation; D010063:Ovum / Q000502:physiology; D011247:Pregnancy; D012309:Risk-Taking; D013094:Spermatozoa / Q000502:physiology; D013997:Time Factors