Cumulative pregnancy rate from one gamete intra-Fallopian transfer (GIFT) cycle with cryopreservation of embryos: a practical mathematical calculation

We evaluated the cumulative pregnancy rate from one gamete intra-Fallopiantransfer (GIFT) cycle plus subsequent cycles in which embryoscryopreserved at the time of the original GIFT cycle were transferred.All patients who had their first GIFT cycle in our centre betweenJanuary, 1989 and March, 1991 were included. Ovarian stimulationwas accomplished with leuprolide acetate (luteal phase protocol)and a combination of follicle stimulating hormone and humanmenopausal gonadotrophin. GIFT was performed with three to fiveoocytes. Excess oocytes were inseminated and good quality embryoswere cryopreserved at the 2- to 4-cell stage with 1–2propanediol. When the GIFT cycle did not result in a pregnancy,uterine transfer of cryopreserved embryos was carried out insubsequent unstimulated cycles. A total of 97 patients had GIFTand 46 pregnancies were achieved (47.4%). A total of 51 patients(52.5%) had embryos frozen; of these, 21 were from the non-pregnantgroup (41.1%) and 30 from the pregnant group (65.2%) (P <0.05). Up to now, 22 of them have undergone a frozen—thawedembryo transfer cycle, and two of them achieved a pregnancy.Based on these data, patients having a GIFT could theoreticallyexpect a cumulative pregnancy rate of 52.2%.