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

Abstract

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.

PIP: The antifertility and obstructive effects toward spermatozoa of a continuous low-dose progestogen contraceptive are examined in this study. Scanning electron microscopy (SEM) observations were correlated with sperm penetration tests carried out on cervical mucus. 11 healthy women aged 19 to 36 who were using no oral contraceptives were studied for 2 consecutive cycles. During the 2nd cycle, the women took a single, daily low-dose progestogen pill (350 ug of Norgestrienone) from the 1st till the 13th day. Blood samples were collected for determination of plasma estrogen levels, which were found to be normal during the control cycle. The progestogen was found to dramatically alter midcycle cervical mucus at the macromolecular level. The meshwork constituting the infrastructure of cervical secretion appeared to be greatly tightened by the treatment, giving the woof a general appearance typical of cervical mucus in the late luteal phase. The mucus framework revealed a tangle of micelles, and sperms leaving the seminal pool in the vagina were faced with such a succession of exhausting physical obstacles that they were unable to penetrate the uterine cavity. The SEM data shows that rendering the midcycle cervical mucus hostile interferes with sperm transport and this probably accounts for the effectiveness of the continuous low-dose progestogen therapy.