Effects of clomiphene citrate on cervical mucus: analysis of some influencing factors

A multicenter study was performed to investigate the effects of a standard dose of clomiphene citrate (100 mg/day from day 5 of the cycle for five days) on the quality of cervical mucus. A total of 82 cervical mucus samples from 60 infertile patients (15 with secondary amenorrhea, 16 with delayed ovulation, 15 with anovulatory cycles, 14 with oligomenorrhea) was examined on the day of maximum follicular diameter. As a control we studied 54 cervical mucus samples from 47 patients with documented tubal sterility or infertile partners, who had spontaneous cycles with normal rhythm. Cervical mucus was unfavorable in 59% of the treatment cycles compared with 11% of the control cycles. Clomiphene citrate's antiestrogenic effect on cervical mucus was found to be related to the length of time between the last drug administration and the day of maximum follicular diameter (delta days), since cervical mucus was favorable in 64% of the cycles with a delta days more than 6 and in only 16% of the cycles with a delta days of 6 or less. Clomiphene citrate thus seems able to decrease cervical mucus quality. This could be one of the causes of the discrepancy between the rates of ovulation and pregnancy reported in patients treated with this drug.