Live Births with a Single Stimulation Cycle
How Many Oocytes are Needed to Achieve Multiple Live Births?
Researchers, Denis A. Vaughan, Angela Leung, Nina Resetkova, Robin Ruthazer, Alan S. Penzias, Denny Sakkas, and Michael M. Alper wanted to study how many infertility patients would complete and average-sized family after a single, complete IVF cycle. An average-sized family includes at least 2 live births. There are many significant barriers keeping infertile couples from successfully achieving this goal. This study cites the most common risk is related to controlled ovarian hyper-stimulation (COH). This intents to produce a group of oocytes, allowing the transfer of the best embryos, leading to the question of what the target number of oocytes is in a fresh IVF cycle. The biggest concern with this is that high oocyte yield cycles may be associated with ovarian hyperstimulation syndrome (OHSS). Though most cases of OHSS are mild, it can come with serious consequences such as pain, illness or even death.
Methods & Protocols
Patients included in this study
The authors reviewed all homologous cycles with oocyte retrieval from January 2012 to December 2014. Only patients who retrieved at least one oocyte after the stimulation cycle were included. Oocyte groups were presented based on what the researchers considered very low, low, average, good, and high oocyte yield and were used as a continuous variable. Then, patients were divided into five groups based on the number of oocytes retrieved: 1-3, 4-9, 10-14, 15-25, >25 oocytes. These groups will be referred to as groups 1 to 5.
Two separate analyses were then performed; one for patients who underwent a single ovarian stimulation cycle with retrieval and used all the embryos resulting from that cycle, and the second being for patients who had frozen embryos remaining at the conclusion of the study period. The primary outcome was less than or equal to 2 live births and secondary outcomes were less than or equal to 1 live births in the fresh cycle, less than or equal to 1 true live births from fresh or frozen cycles, number of usable blastocysts, and clinical pregnancy rate.
Embryos were transferred either on Day 3, the cleavage stage, or Day 5, the blastocyst stage, on a case-by-case basis. Throughout the study, the authors noticed a growing trend toward increasing the proportions of blastocysts transfers.
Results & Conclusion
Pregnancy outcomes per patient
The average age of the patients were 38, 36.6., 35.2, 34.5 and 33.8 years in groups 1-5. The researchers investigated differences in fertilization rates, blastocyst rates, and clinical pregnancy rates between each group. When at max, 15 oocytes were retrieved, the pregnancy rate was significantly higher than less than 15 oocytes. The researchers also found that 498 patients out of 2,226 would achieve at least 2 live births.
Overall, from the research the authors found that one cycle with high oocyte yield is a favorable way to plan IVF treatment. In fact, they’ve found that almost a quarter of the patients could safely achieve 2 live births with just one stimulation cycle!