Billings - Relationship between daily mucus characteristics and levels of fecundability

With the collaboration of Italian centres providing services on natural family planning, a prospective study collected data on more than 2000 menstrual cycles of 193 women. A database was constructed using information on the daily characteristics of cervical mucus and episodes of intercourse. Taking the day of peak mucus as a conventional marker of ovulation, the database identified the length (12 days) and location of a 'window' of potential fertility with the highest level of conception probability being confined to the central five to six days. Univariate analysis provided evidence of the impact on fecundability of the woman's age and the basic infertile pattern of a cycle. Several analytical approaches highlighted the relationship between daily mucus characteristics and levels of fecundability.