Risks of rhythm method of birth control.
D000022:Abortion, Spontaneous / Q000209:etiology; D000818:Animals; D002869:Chromosome Aberrations; D003075:Coitus; D000013:Congenital Abnormalities / Q000209:etiology*; D003267:Contraception / Q000009:adverse effects*; D005193:Family Planning Services; D005260:Female; D005306:Fertilization; D006168:Guinea Pigs; D006801:Humans; D008598:Menstruation; D008722:Methods; D010060:Ovulation; D010063:Ovum; D011247:Pregnancy; D011248:Pregnancy Complications / Q000209:etiology*; D011817:Rabbits; D051381:Rats; D012725:Sexual Behavior; D013997:Time Factors