Implantation rates subsequent to the transfer of embryos produced at different phases during double stimulation of poor ovarian responders.

To compare the implantation capacity of embryos obtained at different phases of double stimulation (DS) of poor ovarian responders, 153 DS cycles were analysed retrospectively. As part of the DS protocol, antral follicles were stimulated continuously during both the follicular and luteal phases. Fresh embryos obtained in both phases were cryopreserved and transferred in the next artificial cycle. The mean number of oocytes retrieved, MII oocytes and zygotes with two pronuclei was significantly higher for collections during luteal-phase stimulation. Furthermore, the dose of exogenous gonadotropin administered was higher during the luteal phase. The rate of clinical pregnancy and embryo implantation increased progressively from pure follicular phase embryos to mixed embryos to pure luteal phase embryos. Embryos produced during the luteal phase resulted in higher implantation rates.