Reproductive outcome of fresh or frozen-thawed embryo transfer is similar in high-risk patients for ovarian hyperstimulation syndrome using GnRH agonist for final oocyte maturation and intensive luteal support.

Background: Triggering ovulation by GnRH agonist (GnRHa) in GnRH antagonist IVF protocols coupled with adequate luteal phase support has recently been suggested as a means to prevent ovarian hyperstimulation syndrome (OHSS). Our objective was to examine the outcome of fresh embryo transfer (f-ET) after triggering ovulation by GnRHa and providing intensive luteal phase supplementation, compared with that of the next first frozen-thawed embryo transfer (ft-ET) after cycles with the same protocol and cryopreservation of all the embryos.

Methods: We performed a cohort study at a university-based IVF clinic. The study population was patients at high risk for OHSS. A daily dose of 50 mg i.m. progesterone in oil and 6 mg of oral 17-β-estradiol initiated on oocyte retrieval day in the f-ET group (n= 70). In the ft-ET group (n= 40) the embryos were cryopreserved and transferred in the next cycle.

Results: The live birth rate per f-ET was 27.1 versus 20% in the ft-ET groups [P = 0.4; rate ratio = 1.36 (0.65-2.81)]. The implantation, pregnancy and spontaneous abortion rates were comparable in both groups. None of the patients developed OHSS.

Conclusions: In this observational cohort study, we showed that triggering ovulation with GnRHa and intensive luteal phase support is a promising new modality to prevent OHSS without the cost of cycle cancellation, ET deferral and reduced clinical pregnancy rates. Confirmation of these findings by RCTs is now required.