LOW FERTILIZATION: statistical definition and clinical relevance.

Area of Science:

• Reproductive Medicine
• Biostatistics
• Infertility Research

Background:

• Reduced fertilization rates pose significant challenges for patients and embryologists.
• Distinguishing pathological causes from statistical variability in fertilization is crucial for effective treatment.

Purpose of the Study:

• To develop and validate a statistical metric, LOW FERTILIZATION, to identify a distinct pathological entity underlying reduced fertilization.
• To assess the frequency, predictive factors, and recurrence risk of LOW FERTILIZATION in a real-world population.

Main Methods:

• A statistical model based on binomial distribution was employed, defining LOW FERTILIZATION as an outcome with <5% expected probability under the null hypothesis.
• The model incorporated assumptions of constant fertilization probability (P) based on Istanbul Consensus benchmarks and absence of underlying clinical conditions.
• The metric was applied to real-world data from 2653 women undergoing fertility treatments.

Main Results:

• LOW FERTILIZATION was observed in 4.5% of cycles, with higher incidence in ICSI (5.2%) compared to cIVF (3.6%).
• Severe male factor infertility was significantly associated with LOW FERTILIZATION in ICSI cycles (aOR=2.60).
• The recurrence risk of LOW FERTILIZATION was elevated (aOR=3.70), particularly after ICSI in both cycles (aOR=7.26).

Conclusions:

• The LOW FERTILIZATION metric successfully identifies a rare but distinct clinical condition associated with reduced fertilization.
• This metric serves as a valuable tool for future research into the factors contributing to this condition.
• The findings underscore the importance of statistical evaluation in understanding and managing reduced fertilization outcomes.