The time-course from germinal-vesicle break down (GVBD) to first polar body extrusion (PBE) in rescued in vitro maturation (r-IVM), a prospective study on time lapse imaging

Abstract

To access the time-course and associated factors of oocyte maturation from GVBD to PBE in r-IVM. Non-comparative; Prospective. Patients underwent intracytoplasmic sperm injection and had at least one GV oocyte after denudation were included. After denudation, GV oocytes were cultured in G-IVF® media and placed into a time-lapse incubator. Images were taken every 10 mins for 144 hours. The GVBD and PBE time were counted. Patient’s age, protocol, base and hCG day luteinizing hormone (LH), base follicle stimulation hormone (FSH), base and hCG day estradiol (E2), immaturation rate, and big follicle acquisition rate (BFA, BFA=[N of retrieval oocyte]/[N of follicles≥12mm]) were recorded for univariable clustered Cox regression [1,2]. Variables (p <0.3) were chosen for multivariable analysis. Hazard ratio (HR) with 95% confidence interval (95%CI) were reported. There were 36 patients (79 GV oocytes) recruited. 12 GV oocytes did not mature. The overall time-course was 23.2h (95%CI 21.3-24.4h). The baseline and analysis results are shown in Table I. The BFA<1 means GV oocytes were from big follicles. GV oocytes in group BFA<1 showed shortened time-course in both univariable (HR 2.43, 95%CI 1.49-4.35, p<.001) and multivariable analysis (HR 2.38, 95%CI 1.32-4.35, p=0.004). The adjusted chance of maturation in group base E2 concentration >50 was revealed to be two times greater (HR 2.00 95%CI 1.06-3.81, p=0.034). We first demonstrate a precise time-course of GVBD to PBE in stimulated cycles, which can contribute significantly to catching the fertilization window in r-IVM as well as traditional IVM. We found that GV oocytes from big follicles or patient with higher base E2 have higher chance of maturation. These findings give clues for oocyte and follicle development, but further studies are needed to confirm.Table ICharacteristicsBaselineUnivariable analysisMultivariable analysisHR95%CIP-valueHR95%CIP-valueAge (year)35.89±3.21 ≥35 (n [%])24 (66.67)RR <35(n [%])12 (33.33)0.950.83-1.10.5051.160.53-2.520.715Stimulation protocol Long (n [%])9 (25.00)RR Antagonist (n [%])27 (75.00)0.760.46-1.270.2960.660.42-1.030.068Base FSH (IU/l)6.40 (5.55-7.98)0.980.88-1.10.761NCBase LH (IU/l)4.55 (4.05-6.68)1.000.91-1.110.965NCLH on hCG day (IU/l)3.350.980.91-1.060.655NCImmaturation rate (%)23.41±11.210.970.96-0.990.0100.980.96-1.010.198Base E2 (pmol/l)104.2±48.28 <50 (n [%])4 (11.10)RR ≥50 (n [%])32 (88.90)1.370.92-2.050.1242.001.06-3.810.034E2 on hCG day (pmol/l)11550 (8433.50-15167.00)0.780.49-1.260.317NCBFA (%)108.01 (81.77-132.35) <1 (n [%])21 (58.30)R ≥1 (n [%])15 (41.70)2.431.49-4.35<.0012.381.32-4.350.004R=Reference.NC=Not Chosen. Open table in a new tab