Experimental study of cervical blockage induced by continuous low-dose oral progestogens

An investigation correlating scanning electron microscopic observations with sperm penetration tests carried out on cervical mucus under the influence of low-dose continuous progestogen (Norgestrienone) is presented. The results demonstrate that such type of contraceptive is involved in drastic alterations of mid-cycle cervical mucus at the macromolecular level. The meshwork which constitutes the infrastructure of the cervical secretion appears to be greatly tightened as a result of the treatment, thus giving the woof a general appearance typical of cervical mucus in the late luteal phase. The immobilizing effect of such modified mucus on spermatozoa is demonstrated and the duration of effectiveness after the administration of a last pill on the morning of day 13 is determined.