O-118 Morphokinetic embryo behavior in low-prognosis patients according to the POSEIDON criteria: an analysis of 3326 injected oocytes
Authors: Setti A , Braga D , Provenza R , Guilherme P , Iaconelli Junior A , Borges Junior E 
Published: June 2023

Abstract

Study question
Do embryo quality and morphokinetic behavior differ in the four groups of low-prognosis women as stratified by the POSEIDON criteria?

Summary answer
Embryo quality and morphokinetic behavior differ across the POSEIDON groups, being more favorable in POSEIDON group 1, as well as were implantation and miscarriage rates.

What is known already
Poor ovarian responders (POR) represent 9-24% of patients undergoing ovarian stimulation, and the clinical management of these patients remains a challenge in everyday practice. In an attempt to standardize the diagnosis of POR, the medical community developed the Bologna Criteria and then shifted to the Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number (POSEIDON). Embryo monitoring with timelapse imaging (TLI) may allow the identification of morphokinetic events potentially affected by ovarian response. The aim of this study was to compare embryo quality, and speed and pattern of cell divisions in the four groups of POR as stratified by the POSEIDON criteria.

Study design, size, duration
This cohort study included low-prognosis patients undergoing their first intracytoplasmic sperm injection (ICSI) from Mar/2019 to Apr/2022 at a private-university affiliated IVF center, who met the POSEIDON criteria. A total of 3326 injected oocytes from 846 women were analyzed. Kinetic markers from the point of insemination were recorded. Generalized mixed models followed by Bonferroni post hoc were used to compare morphokinetics among the POSEIDON groups. The post hoc achieved power was &gt; 80%.

Participants/materials, setting, methods
Injected oocytes were cultured in the EmbryoScope+ incubator, which recorded the following kinetic markers: timing to pronuclei appearance and fading (tPNa and tPNf), two (t2), three (t3), four (t4), five (t5), six (t6), seven (t7), and eight cells (t8), morulae (tM), start of blastulation (tSB) and blastulation (tB). Durations of second and third cell cycles (cc2 and cc3) and timing to complete synchronous divisions s1, s2, and s3 were calculated. The KIDScore ranking was recorded.

Main results and the role of chance
The results from the generalized mixed models followed by Bonferroni post hoc for the comparison of means among groups showed that embryos derived from patients in the POSEIDON groups 2, 3 and 4 showed significantly slower divisions compared to those from POSEIDON 1 group (Table 1). The KIDScore rank was significantly lower for embryos derived from POSEIDON groups 2, 3 and 4 (2: 4.4 ± 0.7 vs. 3: 4.2 ± 0.2 vs. 4: 3.0 ± 0.4) compared to those derived from POSEIDON 1 group (4.8 ± 0.1, p &lt; 0.001). Group POSEIDON 1 also showed improved implantation (26.9% vs. 2: 22.4% vs. 3: 20.0% vs. 4: 14.0, p &lt; 0.001) and miscarriage rates (5.6% vs. 2: 31.2% vs. 4: 50.0%, p = 0.013).

Limitations, reasons for caution
The use of historical cohort groups is a drawback. Despite the eligibility criteria for inclusion in the analysis, potential differences in the baseline characteristics cannot be ruled out.

Wider implications of the findings
Embryo development was more favorable in POSEIDON group 1, suggesting a direct relationship between oocyte quantity and quality, and that oocyte quality is determinant of embryo development. These show the reasonability of classifying POR by the POSEIDON criteria, providing information for the appropriate counselling of POR regarding their possible prognosis.

Trial registration number
N/A