Post-partum cervical mucus: biological and rheological properties

In this study we have evaluated the score, sperm migration and ultrastructural characteristics of cervical mucus present in amenorrhoeic women under exclusive breastfeeding at 30, 60, 90, 120, 150 and 180 days post-partum. Periovulatory mucus samples from seven normally cycling women were used as a control. The average scores of post-partum and periovulatory mucus were 4.6 +/- 0.4 and 14.1 +/- 0.5 respectively. Twenty-one (39%) of the 54 post-partum cervical mucus samples and all (100%) periovulatory mucus samples allowed sperm migration. Positive sperm migration into post-partum mucus was observed at all time intervals studied. The only parameter that correlated with sperm migration into post-partum mucus was ferning formation. Sperm migration was obtained in all post-partum mucus samples with a score greater than 8, but samples with scores between 2 and 7 also showed sperm penetration. Scanning electron microscopic studies showed the characteristic spongy appearance of periovulatory mucus. Post-partum mucus was formed by a dense mesh (rocky appearance), when samples were generally unable to sustain sperm migration, but samples where sperm migration occurred showed small areas of spongy mucus mixed with areas in which a dense mesh and high cellularity was observed.