Efficiency of oocyte cryopreservation: a meta-analysis

Area of Science:

• Reproductive Medicine
• Embryology
• In Vitro Fertilization

Background:

• Oocyte cryopreservation is a key technique in assisted reproductive technologies.
• Comparing the efficacy of cryopreserved oocytes versus fresh oocytes in IVF is crucial for optimizing treatment outcomes.

Purpose of the Study:

• To evaluate the efficiency of oocyte cryopreservation, specifically slow-freezing (SF), in comparison to in vitro fertilization (IVF) using unfrozen oocytes.

Main Methods:

• A meta-analysis was conducted comparing IVF-intracytoplasmic sperm injection (ICSI) cycles using cryopreserved oocytes (1996-2004) with those using unfrozen oocytes (2002-2003).
• Slow-freezing (SF) protocols were analyzed, while vitrification (VF) data was limited due to low pregnancy rates before June 2005.
• Key outcome measures included fertilization rates, clinical pregnancy rates, live-birth rates, and implantation rates.

Main Results:

• Live-birth rates per thawed oocyte were 1.9% for SF and 2.0% for VF (pre-June 2005).
• IVF with unfrozen oocytes demonstrated significantly higher rates of fertilization (OR 2.22), live birth per injected oocyte (OR 1.5), and implantation (OR 4.66) compared to SF.
• Improved pregnancy rates were observed with VF after June 2005, suggesting advancements in the technique.

Conclusions:

• In vitro fertilization success rates are significantly lower with slow-frozen (SF) oocytes compared to unfrozen oocytes.
• Oocyte cryopreservation via SF is justified for medical fertility preservation but its elective application needs further study.
• While vitrification (VF) shows promise with improved pregnancy rates, further research is necessary to confirm its efficiency and safety.