Can you ever collect too many oocytes?

Area of Science:

• Reproductive Medicine
• In Vitro Fertilization (IVF)
• Ovarian Stimulation

Background:

• Previous suggestions indicated a decrease in fresh embryo transfer success rates when over 15 oocytes are collected.
• This counterintuitive notion prompted an analysis of recent IVF unit data to investigate the relationship between oocyte yield and success.

Purpose of the Study:

• To determine if increasing oocyte yield beyond a certain threshold improves pregnancy and live birth rates.
• To investigate the potential for diminishing returns or adverse effects with a high number of oocytes collected during IVF.

Main Methods:

• Retrospective analysis of 7697 stimulated IVF/ICSI cycles over two years (August 2010 - July 2012).
• Outcomes (clinical pregnancy, live birth) were analyzed in relation to the number of oocytes collected.
• Logistic regression and generalized estimating equations were used for statistical analysis.

Main Results:

• Clinical pregnancy and live birth rates increased with oocyte yield, from 10.2% and 9.2% (1 oocyte) to 37.7% and 31.3% (>16 oocytes).
• Regression modeling showed success rates generally increased or remained stable with more oocytes collected.
• Embryo cryopreservation rates increased significantly with oocyte yield; Ovarian Hyperstimulation Syndrome (OHSS) risk and fresh transfer cancellations showed a slight increase above 16 oocytes.

Conclusions:

• The study suggests that collecting a high number of oocytes does not necessarily decrease clinical pregnancy and live birth rates.
• Data become sparse above 15 oocytes, making it difficult to confirm continued increases in success rates.
• While high oocyte yield is generally beneficial, the increased risk of OHSS with aggressive stimulation is a significant concern.