Cervical Softening - Anatomy & Physiology

The cervix retains the foetus in the uterus. Connective tissue resists stretch, allowing distension of the uterine body whilst maintaining the cervix in a closed state. For the foetus to move out of the uterus, the cervix must soften or 'ripen'.

The cervix is composed of:

• Collagen fibre bundles: helical strands of amino acids bound together to form fibrils
• Proteoglycan Matrix: protein core with Glycosaminoglycan branches (GAGs). GAGs determine the degree of collagen fibre aggregation. An increased GAG content reduces collagen aggregation and vice versa.

Cervical softening involves two changes in the intracellular matrix:

• Reduction of collagen fibres
• Increase in GAGs to decrease aggregation of the remaining collagen fibres.

The cervix produces:

• Prostaglandin E2 (PGE2)
• Prostacyclin (PGI2)
• Prostaglandin F2α (PGF2α)

Prostaglandins are thought to cause cervical softening, production increases at term and during parturition.

• Prostaglandins may induce cervical softening by:
  • Inducing collagen breakdown
  • Altering GAG/Proteogylcan composition