A prospective field trial of the "ovulation method" of avoiding conception.
D000328:Adult; D002582:Cervix Mucus; D003075:Coitus; D005069:Evaluation Studies as Topic; D005193:Family Planning Services; D005260:Female; D006801:Humans; D008598:Menstruation; D010061:Ovulation Detection / Q000379:methods*; D010298:Parity; D011247:Pregnancy; D011446:Prospective Studies