Two versus three embryos for transfer on day 3: influence of female age and embryo quality on outcome

Abstract

Objective: The objective of this study was to determine the optimal number of embryos to transfer on day 3 in females up to age 38. The dual goals are to maintain a high pregnancy rate and minimize the multiple pregnancy rate. Design: This is a retrospective study with data collected from January 1999 through March 2003. All embryo transfers were performed on day 3 after oocyte retrieval and excluded any oocyte donor cases. Patients were classified by age into one of two groups: females <35, or females >35 and <38. Outcome comparisons (ongoing pregnancy rates defined as presence of a heart beat at 9 weeks gestation) were made by Chi-Square analysis. Only patients with at least 3 embryos at transfer were included in the data analysis. Materials and Methods: All patients underwent an ovarian stimulation protocol using either a GnRH agonist prior to stimulation with gonadotropins, or a GnRH antagonist following gonadotropin stimulation. Oocyte retrieval was performed 36 hrs post hCG administration and embryos were transferred approximately 72hrs post oocyte retrieval. Patients utilizing either standard IVF or ICSI were included in this study. Embryos were cultured in commercially prepared media and graded for quality (cell stage, degree of fragmentation, symmetry of blastomeres) immediately prior to transfer. The highest quality embryos available were chosen for transfer. Results: For the <35 age group, it was found that patients receiving 2 high quality embryos (lead embryo at least 8 cells and of the highest grade) at transfer (n=141) had an ongoing pregnancy rate of 55% while those receiving 3 such embryos (n=196) had an ongoing rate of 56% (P>.05). The singleton, twin and triplet rate for pregnancies of patients receiving 2 embryos was 62%, 38%, and 0%, respectively. Patients receiving 3 embryos had a singleton, twin, and triplet rate of 55%, 34 % and 11%, respectively. When the >35 and <38 age group was examined, it was found that the ongoing pregnancy rate of those patients receiving 3 embryos meeting the same criteria (lead embryo at least 8 cells of the highest grade) (n=123) was 53%. Those receiving 3 embryos had singleton, twin and triplet rates of 55%, 34%, and 8%, respectively (P>.05 when compared to <35 group). As there were no patients in this age group that electively chose only 2 embryos for transfer, these data cannot be directly compared to those of the <35 group receiving 2 embryos. Conclusion: These data raise an interesting possibility for the age group between 35 and 38. It is clear that in the under 35 age group, 3 embryos offer no advantage over 2 embryos when high quality embryos are available for transfer. Moreover, the addition of a third embryo in this group does not increase the overall pregnancy rate-only the high order multiple pregnancy rate (triplets). The fact that the 35–38 age group receiving 3 embryos displayed almost identical pregnancy rates as the under 35 group receiving 3 embryos and that the singleton, twin and triplet rates were not different between the groups suggests that even the older group may benefit from having only 2 high quality embryos transferred. These data suggests doing so would not compromise overall pregnancy rates but would have the benefit of reducing the high order multiple rates. Furthermore, these data fully support the SART guideline of transferring only 2 embryos in younger patients that have a good prognosis. In addition, these data suggest that extending that guideline to include patients up to 38 with a good prognosis may be justified.