Effects of the anti-oestrogens, clomiphene and tamoxifen, on the cervical factor in female infertility.

The anti-oestrogens clomiphene and tamoxifen are successful therapeutic agents in the induction of ovulation but the associated pregnancy rates are low. One cause for this may be a direct anti-oestrogenic effect on cervical mucus, reducing its sperm penetrability. This potentially adverse effect has been shown to occur with clomiphene. In this study the effects of clomiphene and tamoxifen on the cervical factor are compared in women who were anovulatory or had defective ovulation. Forty fully investigated infertile women were randomly allocated to different treatment sequences after being observed for three control cycles. A double-blind placebo technique was used with four different treatment regimes. Serial serum progesterone and oestradiol were assayed. Cervical mucus from the periovulatory phase was assessed by means of the cervical score and in vitro sperm penetration tests. Both these anti-oestrogens can affect cervical mucus but their effect seems to be related more to the end-organ sensitivity of the individual than to a specific action of the drug per se.