Supplementation of clomiphene citrate cycles with Cimicifuga racemosa or ethinyl oestradiol – a randomized trial

The anti-oestrogenic activity of clomiphene citrate (CC) on the cervical mucous and endometrium may be the reason for the relatively low pregnancy rates in CC induction cycles. Various follicular-phase supplements have been tried to improve cycle outcome in these patients. This study compared follicular-phase supplementation with either phytoestrogen (PE) or ethinyl oestradiol (EE) in CC induction cycles for the treatment of unexplained infertility. A total of 134 patients were randomly allocated to each treatment group (67 each). The PE group needed significantly fewer days for adequate follicular maturation, had a thicker endometrium and higher oestradiol concentration at the time of human chorionic gonadotrophin injection (all P < 0.001). The PE group had higher luteal-phase serum progesterone compared with the EE group. No significant difference was found regarding clinical pregnancy rates (14.0% versus 21.1%, respectively). In conclusion, the cycle characteristics in unexplained infertility women treated with clomiphene citrate induction and timed intercourse improved after follicular-phase supplementation with PE compared with EE supplementation. Further studies are needed to confirm the mechanism beyond these effects.