Decrease in clinical pregnancy rate in patients with better prognosis: laboratory alarm activated

Abstract

Study question: Colud the decline in IVF laboratory results observed in our center be influenced by air quality, despite having air filtration equipment (VOC and HEPA filters) and positive pressure? Summary answer: The decrease in clinical pregnancy in patients <40 years of age observed in our center would seem to be due to causes unrelated to the laboratory environment, which is under the greatest protections in terms of air filtration. What is already known: A wide range of factors can affect the outcome of IVF. Within the laboratory, gametes and embryos can be affected by factors associated with the laboratory environment, equipment, contact materials, methodology and the personnel themselves. Study design: Cross-sectional, analytical study. Materials and Methods: From 2018 to 2022, annual clinical pregnancy rate by fresh transfer for patients <40 years old (Clinical <40) gradually decreased, reaching lower values than those established as Center’s reference (35%). Different laboratory variables were analyzed, without finding a direct relationship. A strict selection of patients transferred in the fresh blastocyst stage was carried out. For these patients with the best prognosis, the clinical pregnancy rate (Clinical Selection), their average age (mean ± SD) and the percentage of annual low responders (patients with less than 4 MII oocytes) were calculated for each year, within the period under study. As an environmental control, the annual clinical pregnancy rate of recipients of donated oocytes (Clinical OD) was calculated. Annual rates were analyzed using Chi square and the means of annual ages were compared using ANOVA (significant difference if P<0.05). Main results: Clinical selection rate decreased on the studied period, being only statistically significant in 2022. However, Clinical OD (environmental control) did not show this pattern. Regarding selected patient population, average annual age was homogeneous and annual percentage of low responders increased significantly. Limitations: Study conducted in a single center. Wider implications of the findings: It would seem that the application of biosafety standards in the IVF laboratory means that clinical results are not affected despite prolonged adverse environmental events over time. As a consequence of the significant annual decrease in the ovarian reserve in selected patients, there are less oocytes available to inject. This take off the embryologist the chance of choosing the best embryo for being transferred. This could be one of the reasons why the clinical pregnancy rate decreases.