Self-observation of the cervix to distinguish days of possible fertility.
D002582:Cervix Mucus; D002584:Cervix Uteri; D003267:Contraception; D005260:Female; D005298:Fertility; D006801:Humans; D010060:Ovulation; D012106:Research
CERVIX MUCUS; CERVIX UTERI; CONTRACEPTION; OVULATION