[The Billings method].
D003267:Contraception; D003268:Contraception Behavior; D019049:Developed Countries; D003906:Developing Countries; D005069:Evaluation Studies as Topic; D005193:Family Planning Services; D007390:International Agencies; D010061:Ovulation Detection; D012746:Sexual Abstinence; D014944:World Health Organization
Cervical Mucus Method; Contraception; Contraception Failure; Contraceptive Usage; Developed Countries; Developing Countries; Evaluation; Family Planning; Family Planning, Behavioral Methods; International Agencies; Natural Family Planning; Sexual Abstinence; Who