Abstract Study question We compared a sperm selection protocol using cumulus oophorus complexes with a swim up preparation, evaluating the effects on sperm parameters and ICSI outcomes Summary answer Spermatozoa selected using cumulus oophorus complexes showed higher rates of normal morphology, good motility compared with basal semen and the traditional pellet swim up protocol. What is known already It is known that the head of a mature spermatozoa has a hyaluronan receptor that allows them to bind with hyaluronan acid. Cumulus oophorus complexs (COCs) extracellular matrix is made mainly by hyaluronic acid (HA). Various studies have confirmed the importance of COCs in fertilization, demonstrating that spermatozoa that are able penetrate through a layer of COCs are more likely to have a normal morphology and be more effective in producing acrosome reactions than spermatozoa that are not able to do. Moreover, these spermatozoa have been shown to have higher chromatin integrity and zona-binding capacity, resulting in increased fertilization competence. Study design, size, duration A prospective study was conducted between July and December 2022. A total of 50 participants were recruited for the study, randomly selected between patients attending ICSI. The patients were classified as group A when the sperms were selected using pellet swim up and COC selection and as group B when it was used pellet swim up treatment alone. Patients older than 39 years, with endometriosis or repeated IVF failure or severe male factor were excluded. Participants/materials, setting, methods 3 drops of 30 mlt aligned and connected each other were prepared, covered with mineral oil. In group A, in the middle drop, was transferred COC fragments, while the central drop was empty in group B. In the left drop were added 20 mlt of sperm suspension after swim up, and from the right drops were recovered the sperms after passing the middle drop with or without COC, that were used for ICSI treatment. Main results and the role of chance The aim of the study was to verify the effectiveness of COCs, collected after ovarian stimulation, in selecting the best sperms to be used in ICSI procedure. No statistical difference was found between group A and B in the median age of female patients, FSH/LH units administred, E2 and endometrium thickness at triggering using hCG, in the sperm concentration, motility and normal morphology in the baseline seminal samples. We found a statistical difference in the traditional seminal parameters comparing the two different treatments. In particular, we found an higher rates of sperms with rapid and progressive motility and normal morphology in group A between basal semen sample and after sperm selection using COC filter (86.7 vs 31.3%; 8.2 vs 4.4 %). We found a lower sperm concentration in group A vs group B after sperm treatment (2.3 vs 4.7 M/ml), and an higher rates of rapid progressive motility and normal morphology in group A vs group B (86.7 vs 38.6 %; 8.2 vs 4.6%). We found an higher but not statistically significative pregnancy and implantation rates in group A compared with group B probably because of the limited number of patients analyzed (25 vs 19.2 %; 25 vs 20.6%) Limitations, reasons for caution The study was conducted on a small participant cohort. We analyzed the traditional sperm parameters, but it is necessary to evaluate the chromatine integrity of the sperms after COC selection to confirm that the higher sperm competence in fertilization and embryo development could be based on a better genetic pattern Wider implications of the findings Data seem to demonstrate that the use of COC allows to select higher competent sperms if compared with traditional pellet swim up treatment. The clinical and biological ICSI outcomes seem to be improved by COC treatment but it is necessary to increase the sample size in future experimental trial Trial registration number not applicable

BACKGROUND Live birth per cycle and live birth per embryo transfer are commonly used outcome measures for IVF treatment. In contrast, the assessment of the reproductive efficiency of human oocytes fertilized in vitro is seldom performed on an egg-to-egg basis. This approach may however gain importance owing to the increasingly widespread use of oocyte cryopreservation, as the technique is becoming more established. The aim of the current study is to quantify the reproductive efficiency of the oocyte according to ovarian ageing and ovarian response. METHODS We performed a retrospective analysis of the outcome of all consecutive patients attending for treatment between 1992 and 2009. The outcome in terms of live birth after fresh and cryopreserved embryo transfer per mature oocyte was calculated for 207 267 oocytes retrieved in 23 354 ovarian stimulation cycles. The oocyte utilization rate (number of live births per mature oocyte) was further analysed in relation to the ovarian response. RESULTS The oocyte utilization rate in women in the age of ≤ 37 years remains constant with a mean of 4.47% live birth per mature oocyte [95% confidence interval (CI): 4.32-4.61]. From the age of 38 years onwards, a significantly lower oocyte utilization rate was noted, declining from 3.80% at the age of 38 years to 0.78% at 43 years (P < 0.001). In this 38-43 years age group, oocyte utilization rate was no longer dependent on ovarian response (P = 0.87). CONCLUSIONS The major strength of the study, which is also its weakness, is the fact that we included a large number of cycles performed over a long period of time. According to our results, the oocyte utilization rate between 23 and 37 years of age depends largely on ovarian response and to a much lesser extent on age. From the age of 38 years onwards, the utilization rate depends largely on age and to a much lesser extent on ovarian response. Considering the increased use of oocyte freezing for fertility preservation, these data are extremely valuable as they provide an estimate of the number of oocytes needed to achieve a live birth.

BACKGROUND Pronuclear morphology has been proposed as an indicator of embryo development and chromosomal complement. In this study, the morphology of pronuclear zygotes generated from euploid oocytes [diagnosed by first polar body (PB1) analysis] was evaluated and compared with the configurations observed in chromosomally normal embryos (diagnosed by blastomere analysis). MATERIALS AND METHODS Group 1--238 patients underwent 273 assisted conception cycles in combination with the screening of aneuploidy on PB1 for the chromosomes 13, 15, 16, 18, 21 and 22. Only normal oocytes were inseminated. Group 2--218 patients underwent 318 assisted conception cycles with aneuploidy screening on day 3 embryos. In both groups, oocytes were checked for fertilization and pronuclear morphology at 16 h after insemination. RESULTS Seventy-three percent of zygotes from Group 1 had the configurations with centralized and juxtaposed pronuclei, large-size aligned or scattered nucleoli and PB located in the longitudinal or perpendicular axis of pronuclei. In Group 2, these configurations corresponded to those with the highest proportion of chromosomally normal embryos. Accordingly, in both groups, these configurations had a higher implantation rate than all the others. CONCLUSIONS These observations confirm that some patterns of pronuclear morphology are associated with a higher proportion of euploidy and implantation reaffirming the relevance of this scoring system for the prediction of zygote viability.