Ferning (Cervical Mucus Ferning)
Ferning is the fern-shaped pattern cervical mucus leaves when a drop dries on a slide and is viewed under a microscope. The branches form as salts in the mucus crystallize while the water dries off. It is also written as cervical mucus ferning.
The pattern follows estrogen. Fertile-type mucus is watery and salt-rich, so it ferns in clear branching shapes. The same salts and proteins open the channels that let sperm swim through.1 One study of ten women found that mucus from women with PCOS, now also named PMOS (Polyendocrine Metabolic Ovarian Syndrome), formed an odd, poorly defined crystal pattern when they were not ovulating. Those who did ovulate looked much like the controls.2
A woman charting her cervical mucus pattern reads the same estrogen signal at home.
Cited in this entry
- Campo S, Garcea N. The canalization of cervical mucus in the human fertility. Acta Europaea Fertilitatis. 1991. https://pubmed.ncbi.nlm.nih.gov/1746206/
- Vigil P, Cortés ME, Zúñiga A, Riquelme J, Ceric F. Scanning electron and light microscopy study of the cervical mucus in women with polycystic ovary syndrome. Journal of Electron Microscopy. 2009. https://pubmed.ncbi.nlm.nih.gov/19141465/
This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.
