Is frozen embryo transfer better than fresh embryo transfer in women undergoing intracytoplasmic sperm injection over the age of thirty-five? A single referral centre experience

Abstract

Developments in embryo freezing techniques in recent years have increased the chance of pregnancy after frozen embryo transfers. In this study we aimed to compare the pregnancy outcomes between fresh (ET) and frozen-thawed embryo transfer (FET) and to evaluate the benefits of embryo freezing strategy for a woman of advanced age. A total of 513 ET cycles in women over the age of 35 years, including 397 fresh ET cycles and 116 FET cycles were reviewed. Mean age was 37.7 ± 2.91 years in FET cycles and 38 ± 2.8 in fresh cycles (p = .327). The patients undergoing FET cycles had higher oestradiol levels and progesterone levels on the day of trigger in their previous fresh cycles compared to that of fresh ET cycles (1675 pmol/L versus 991 pmol/L; 1.43 pmol/L versus 0.96 pmol/L; p < .005, respectively). Biochemical pregnancy rates (43% versus 32%; p = .048), clinical pregnancy rates (38% versus 29%; p = .030) and live birth rates (30% versus 19.6%; p = .013) were significantly higher in the FET than in the fresh ET over 35 years of age. IMPACT STATEMENT What is alreday known on this subject? Ovarian stimulation commonly results in the generation of more embryos than are necessary for the fresh embryo transfer. Therefore, cryopreservation and subsequent replacement of frozen–thawed embryos is an integral part of assisted reproductive technique (ART) programs. As IVF technology improved, embryo freezing was performed to allow subsequent transfer if the fresh cycle was unsuccessful. What do the results of this study add? Clinical pregnancy rates and live birth rates were found to be higher in frozen thawed embryo transfer group compared to fresh embryo transfer group over the age of 35. What are the implications of these findings for clinical practice and/or further research? Frozen thawed embryo transfer seems to be a reasonable and favourable method compared to fresh embryo transfer in patients over 35 years.