The effect of follicle size and homogeneity of follicular development on the morphokinetics of human embryos

Optimizing trigger timing in minimal ovarian stimulation for In Vitro fertilization using machine learning models with random search hyperparameter tuning

Various studies have emphasized the importance of identifying the optimal Trigger Timing (TT) for the trigger shot in In Vitro Fertilization (IVF), which is crucial for the successful maturation and release of oocytes, especially in minimal ovarian stimulation treatments. Despite its significance for the ultimate success of IVF, determining the precise TT remains a complex challenge for physicians due to the involvement of multiple variables. This study aims to enhance TT by developing a machine learning multi-output model that predicts the expected number of retrieved oocytes, mature oocytes (MII), fertilized oocytes (2 PN), and useable blastocysts within a 48-h window after the trigger shot in minimal stimulation cycles. By utilizing this model, physicians can identify patients with possible early, late, or on-time trigger shots. The study found that approximately 27 % of treatments administered the trigger shot on a suboptimal day, but optimizing the TT using the developed Artificial Intelligence (AI) model can potentially increase useable blastocyst production by 46 %. These findings highlight the potential of predictive models as a supplementary tool for optimizing trigger shot timing and improving IVF outcomes, particularly in minimal ovarian stimulation. The experimental results underwent statistical validation, demonstrating the accuracy and performance of the model. Overall, this study emphasizes the value of AI prediction models in enhancing TT and making the IVF process safer and more efficient.

Effect of the degree of follicular diameter ≥18mm differentiation on the day of hCG administration to the outcome of controlled ovarian hyperstimulation (COH)

Objective

To explore the impact of the level of differentiation in a minimum of two follicles with a diameter of ≥18 mm on the outcome of controlled ovarian hyperstimulation on the day of human chorionic gonadotropin (hCG) administration.

Methods

Single-center data from January 2018 to December 2021 was retrospectively analyzed for 1,199 patients with fresh embryo transfer for assisted reproduction. The absolute value of the standard deviation of the follicle size of at least 2 follicles ≥18 mm in diameter in both ovaries on the day of hCG was taken as the degree of differentiation of the dominant follicle after ovulation induction, based on the standard deviation response to the degree of dispersion of the data. The degree of follicular differentiation was divided into 3 groups according to the size of the value, and the general clinical conditions, laboratory indexes, and clinical outcomes of the patients in the 3 groups were compared.

Results

Among the three groups, the body mass index (BMI) of the ≤1s group was lower than that of the other two groups (P< 0.05), while the follicle-stimulating hormone (FSH) and Anti-Mullerian hormone (AMH) were higher (P< 0.05), and the implantation rate and clinical pregnancy rate were significantly higher than those of the other two groups (P< 0.01). After multifactorial logistic regression to correct for confounding factors, with the ≤1s group as the reference, the implantation rate, hCG-positive rate, clinical pregnancy rate and live birth rate of embryo transfer in the ≥2S group were significantly lower (P< 0.01). The results of curve fitting analysis showed that the live birth rate decreased gradually with the increase of the absolute standard deviation (P=0.0079).

Conclusion

Differences in follicle diameters ≥18 mm on the day of hCG injection did not have an impact on embryo quality, but had an impact on pregnancy outcomes. The less the variation in follicle size, the more homogeneous the follicle development and the higher the likelihood of live births.

Initial β-hCG levels and 2-day-later increase rates effectively predict pregnancy outcomes in single blastocyst transfer in frozen-thawed or fresh cycles: A retrospective cohort study

To investigate whether the initial beta-human chorionic gonadotropin (β-hCG) levels and their rate of increase differ after single fresh and frozen blastocyst transfers, and whether these values effectively predict pregnancy outcomes. This retrospective cohort study was conducted at the Sisli Memorial Hospital, assisted reproductive technology, and Reproductive Genetics Center in Istanbul, Turkey, between January 2016 and January 2022. Three thousand two hundred thirty-eight single blastocyst transfers with positive pregnancy test results were evaluated. Of these, 738 were fresh transfer cycles and 2500 were frozen-thawed embryo transfer (FET) cycles. β-hCG test results from 9 days after fresh and FET cycles were compared between the groups with biochemical pregnancy, early pregnancy loss, and live birth outcomes. The threshold values were determined for each pregnancy outcome. The rate of increase between the first and second β-hCG tests performed 2 days apart was determined for each pregnancy outcome. Finally, the listed values were compared between the FET and fresh cycle. Mean baseline β-hCG levels were significantly higher in FET cycles than in fresh cycles, regardless of pregnancy outcomes (P < .005). Baseline β-hCG levels were higher in fresh cycles with live births (171.76 ± 109.64 IU/L) compared to biochemical and clinical pregnancy losses (50.37 ± 24.31 and 114.86 ± 72.42, respectively) (P < .001). Live births in FET cycles resulted in higher baseline β-hCG levels (193.57 ± 100.38 IU/L) compared to biochemical and clinical pregnancy loss groups (68.41 ± 51.85 and 149.29 ± 96.99 IU/L, respectively) (P < .001). The β-hCG threshold for live birth for fresh cycles was 116.5 IU/L (sensitivity 80%, specificity 70%, positive predictive value 90%, negative predictive value 54%) and 131.5 IU/L for FET cycles (sensitivity 71%, specificity 68%, positive predictive value 87%, negative predictive value 50%). The percentage of the area under the curve for single fresh blastocyst transfers was 0.81 and 0.76 for frozen transfers. The rate of increase in β-hCG was similar in fresh and FET cycles. Initial β-hCG levels and 2-day increases are effective parameters for diagnosing pregnancy in fresh and FET cycles. The initial β-hCG level was significantly higher in the FET cycles than in the fresh cycles. Predicting outcomes earlier helps clinicians to manage and follow high-risk pregnancies.

Factors influencing the number of mature oocytes and cryopreservable blastocysts in hyperresponder patients triggered with a GnRH analog

PURPOSE

This study aimed to investigate which patient and cycle characteristics may affect the number of mature oocytes and cryopreservable blastocysts in the GnRH analog trigger cases.

METHODS

This was a retrospective cohort study of 2749 GnRHa trigger cycles in patients at risk of OHSS, including a group of PGT patients, between 2011 and 2020 at Istanbul Memorial Hospital, ART and Reproductive Genetics Center. Patient and cycle characteristics were evaluated using the Generalized Linear Mixed Model (GLMM). The number of mature oocytes and the number of cryopreservable blastocysts were evaluated.

RESULTS

A one-unit increase in female age, daily gonadotropin dose, E2 level on day 2, and LH level on trigger day significantly decreased the number of mature oocytes retrieved (p < 0.001) and the number of cryopreservable blastocysts as p < 0.001, p < 0.001, p < 0.001, and p = 0.003, respectively. The duration of GnRH antagonist use also decreased the number of mature oocytes retrieved (p < 0.001) but not the number of cryopreservable blastocysts.

CONCLUSION

The GLMM used in our study showed that a one-unit increase in female age, daily gonadotropin dose, E2 level on day 2, and LH level on trigger day significantly decreased the number of mature oocytes retrieved and the number of cryopreservable blastocysts.

The effect of large follicle puncture and aspiration on the outcomes of IVF-ET in patients with asynchronized follicles under the long GnRH-a protocol: a retrospective cohort study

OBJECTIVE

This retrospective study aimed to explore whether puncturing and aspirating asynchronized large follicles during long GnRH-a protocol COH impacted IVF-ET outcomes.

METHODS

A total of 180 patients with asynchronized follicles during long GnRH-a protocol COH were retrospectively analyzed. They were divided into a puncture group, Group 1 (n = 81), and a non-puncture group, Group 2 (n = 99), according to whether puncture and aspiration were performed on the prematurely developing large follicles. The data of the selected patients were statistically analyzed to assess the effect of large follicle puncture and aspiration during ovulation induction on the final pregnancy results. In addition, we tentatively divided these 180 patients into either Group A (DF ≤ 14 mm) or Group B (DF > 14 mm) according to whether the diameter of the dominant large follicles (DF) exceeded 14 mm at the time of appearance. These two groups were then further divided into four subgroups: Subgroup A1 (DF ≤ 14 mm, patients underwent large follicle puncture), Subgroup A2 (DF ≤ 14 mm, patients did not undergo large follicle puncture), Subgroup B1 (DF > 14 mm, patients underwent large follicle puncture), and Subgroup B2 (DF > 14 mm, patients did not undergo large follicle puncture) based on whether large follicle puncture and aspiration were performed or not, aiming to compare the effects of large follicle puncture and aspiration on the clinical outcomes of patients with dominant large follicles at different time points.

RESULTS

Group 1 exhibited significantly higher oocyte maturation rate (92.3% vs. 88.9%, P = 0.009) and high-quality embryo rate (75.2% vs. 65.7%, P = 0.007) compared with Group 2. No differences were observed in the number of oocytes retrieved, 2PN fertilization rate, clinical pregnancy rate, abortion rate, and live birth rate between the two groups (P > 0.05). When the dominant large follicles' diameter was ≤ 14 mm, the final oocyte maturation rate (92.7% vs. 88.1%, P = 0.023), high-quality embryo rate (72.9% vs. 61.8%, P = 0.047) and live birth rate (54.5% vs. 31.9%, P = 0.043) of Subgroup A1 were significantly higher than those of Subgroup A2. In contrast, when the dominant large follicles' diameter was > 14 mm, no statistical difference was observed in all data.

CONCLUSIONS

Large follicle puncture and aspiration in long GnRH-a protocol COH could improve the oocyte maturation rate and high-quality embryo rate in patients with asynchronized follicles. However, clinical pregnancy and live birth rates were not significantly improved. In addition, when the dominant follicles' diameter did not exceed 14 mm, large follicles puncture and aspiration significantly improved the patient's oocyte maturation rate, high-quality embryo rate and live birth rate.

Efficacy and safety of controlled ovarian hyperstimulation with or without letrozole for fertility preservation in breast cancer patients: A multicenter retrospective study

INTRODUCTION

Fertility preservation (FP) is recommended in young breast cancer (BC) patients before (neo)adjuvant treatment. Letrozole-associated controlled ovarian hyperstimulation (LetCOH) is used worldwide to collect mature oocytes for FP, but its efficacy and safety compared to conventional protocols (cCOH) are still debated.

AIMS

To compare efficacy and safety of FP procedure using LetCOH or cCOH in BC patients in terms of oocyte maturation rate and disease-free survival rates after at least two years of follow-up.

METHODS

This multicenter retrospective study compared outcomes of 107 cycles in 97 non-metastatic BC patients aged ≤40 years who underwent cCOH (n = 56) or LetCOH (n = 41) for FP in CHU-Lille and Erasme Hospital, respectively, between December 2012 and January 2017.

RESULTS

Patients and oncological characteristics were similar except for tumor size and HER2 status which were less favorable in the LetCOH group. Patients underwent adjuvant chemotherapy in 96.4% and 48.8% of the cases in cCOH and LetCOH groups, respectively. Hence, 51.2% of LetCOH patients underwent neoadjuvant chemotherapy (p < 0.001). Estradiol peak at ovulation trigger was lower in LetCOH compared to cCOH group while oocyte maturation rates were significantly higher (p < 0.001), without impacting the final number of mature oocytes collected. Seven and four patients relapsed in LetCOH and cCOH groups, respectively, and one patient died in each group after a median follow-up of four years.

CONCLUSION

LetCOH is as effective as cCOH for FP. At this time point, there were no safety concerns regarding cCOH in the adjuvant setting but a longer follow-up is warranted.

The effect of ovarian follicle size on oocyte and embryology outcomes

OBJECTIVE

To identify relationships between the size of punctured ovarian follicles and subsequent embryology outcomes.

DESIGN

Prospective observational cohort study.

SETTING

Private fertility center.

PATIENTS

One hundred fifty-seven oocyte retrievals performed during the study period.

INTERVENTIONS

The diameter of punctured follicles was ultrasonically measured during routine oocyte collection. The resulting embryos were group-cultured to the blastocyst stage and classified into 8 groups according to follicle size (≤9.5, 10-12.5, 13-15.5, 16-18.5, 19-21.5, 22-24.5, 25-27.5, and ≥28 mm).

MAIN OUTCOME MEASURE

Rate of good-quality blastocysts per follicle puncture.

RESULTS

This study included 4,539 follicle punctures, 2,348 oocytes, 1,772 mature oocytes, 1,258 bipronuclear (2pn) oocytes, and 571 good-quality blastocysts derived from 157 oocyte retrievals. The per-puncture yields of oocytes, mature oocytes, 2pn oocytes, and good-quality blastocysts were associated with the size of the punctured follicle. The rates of good-quality blastocysts per punctured follicle were 2.2% (≤9.5 mm), 6.2% (10-12.5 mm), 11.9% (13-15.5 mm), 14.5% (16-18.5 mm), 18.9% (19-21.5 mm), 17.5% (22-24.5 mm), 15.9% (25-27.5 mm), and 16.0% (≥28 mm). When compared with the overall average, punctures of follicles in groups ≤12.5 mm in diameter had significantly inferior yields of good-quality blastocysts, whereas punctures of follicles in groups 19-24.5 mm in diameter were associated with significantly greater than average yields of good-quality blastocysts. Other groups did not differ significantly from average. No correlation was observed between follicle diameter and ploidy of biopsied blastocysts.

CONCLUSIONS

Punctures of follicles ≤12.5 mm in diameter rarely result in good-quality blastocysts. The yield of good-quality blastocysts progressively increases with follicle size up to approximately 19 mm in diameter, with no substantial decline above that size. The ploidy of the blastocysts that form appears to be unaffected by follicle size.

Evaluation of the Effects of Platelet-Rich Plasma on Follicular and Endometrial Growth: A Literature Review

Platelet-rich plasma (PRP) has been used in several areas of medicine due to its ability to promote tissue regeneration by growth factors and cytokines. This review addresses the use of PRP to rejuvenate ovarian follicles and increase the thickness of the endometrium to receive an embryo. PRP is obtained from the patient's own blood (autologous blood) - a fact that determines a lower chance of rejection reactions. Alpha granules of platelets provide and release supra physiological amounts of growth factors and cytokines, which provide a regenerative stimulus in tissues with low healing potential. In the ovary, PRP and its growth factors stimulate vascularization and recruitment of available primordial follicles that could no longer be otherwise stimulated. The rejuvenation of the ovary by PRP infusion aims to obtain new oocytes in ovaries with low numbers of follicles or low follicular reserve markers. In the preparation of the endometrium, PRP is used for its several growth factors that allow tissue proliferation and endometrial thickening, especially in cases of endometria that are difficult to prepare or that fail to reach an adequate minimum thickness (>7mm). To date, there are few studies of greater expression in the literature that support the use of PRP with the two purposes described above. Thus, although promising, the technique must still be validated by larger clinical trials.

Activin A overexpression promotes rat follicular development through SCF-kit-mediated cell signals

We explored the possible signaling pathway by which activin A induces oocyte maturation. Inhba-overexpressing lentivirus vectors were constructed and transfected into primary granulosa cells in vitro and ovary tissues in vivo in rats. The granulosa cell growth curve was drawn, and antibodies for phospho-Smad2, phospho-Erk5, phospho-Nur77, and stem cell factor (SCF) were prepared for western blot analysis. Protein expression of SCF and C-kit in the rat ovaries was detected by immunohistochemical staining. The rate of granulosa cell proliferation was higher in the Inhba gene overexpression group (INH) than in the control groups (CON group and GFP group) in vitro. Protein expression of SCF and C-kit was higher in the INH group than in the other two groups. phospho-Smad2, phospho-ERK5, P-nur77, and SCF proteins showed positive expression in rat ovarian granulosa cells in each group and were obviously increased in the INH group. Activin A overexpression may promote rat granulosa cell proliferation through Smad2/ERK5/nur77 signaling pathways, and rat granulosa cells overexpressing activin A in vitro showed increased levels of SCF and c-kit proteins.

Follicle size indicates oocyte maturity and blastocyst formation but not blastocyst euploidy following controlled ovarian hyperstimulation of oocyte donors

STUDY QUESTION

Is there is an association between follicle size and the quality of oocytes retrieved from them as judged by ability to achieve the blastocyst stage, blastocyst grades and blastocyst ploidy?

SUMMARY ANSWER

Although follicle size is a valuable predictor of oocyte maturity and is a significant predictor of the ability of a fertilized oocyte to become a quality blastocyst, the ploidy of each quality blastocyst is not related to the size of the follicle from which its oocyte was retrieved.

WHAT IS KNOWN ALREADY

It is unclear whether the oocytes within larger follicles are the best oocytes of the cohort. Although there have been studies examining follicle size in relation to embryo quality, there has been no study relating the incidence of euploidy in embryos to follicle size.

STUDY DESIGN, SIZE, DURATION

The purpose of this study was to examine follicle sizes and the oocytes from those follicles (and the embryos that result from those oocytes) to see if there is an association between follicle size and the quality of oocytes as judged by ability to achieve the blastocyst stage, blastocyst grades and blastocyst ploidy. Follicle sizes for oocytes were assessed both as diameters (mm) and as Z values (expressed as their size relative to the mean and standard deviation of that donor’s follicular cohort). Comparisons were made using cumulative histograms, rolling averages and receiver operator characteristic (ROC) curves and its AUC.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Twenty-two oocyte donors (ages: 24.5 ± 3.5 years) whose recipients would use ICSI for insemination were enrolled in this study. Follicles were aspirated one-at-a-time to be certain that the aspirated oocyte was from the same follicle measured. The follicle measurement (size) was noted in the embryology records. Oocytes were cultured individually throughout their time in the embryology laboratory so that follicle sizes could be uniquely associated with each oocyte. Oocytes and embryos were analyzed according to the size of the follicle from which the oocyte was retrieved.

MAIN RESULTS AND THE ROLE OF CHANCE

Three hundred seventeen oocytes (96.1%) had an associated follicle size. Of the oocytes with follicle sizes, 255 (80.4%) had a polar body (MII), and 60 (18.9%) were immature: 31 (9.8%) with a visible germinal vesicle (GV stage) and 29 (9.1%) with neither a polar body nor a visible germinal vesicle (MI). The incidence of MII oocytes was significantly associated with larger follicle size using either mm (ROC’s AUC = 0.87; P &lt; 0.0001) or Z values (ROC’s AUC = 0.86; P &lt; 0.0001). Among MII oocytes there was no association with follicle size for the appearance of 228 oocytes with two pronuclei (2 PN). Among 2 PN’s, the development of 94 quality blastocysts that underwent trophectoderm biopsy (TE Bx) exhibited a significant association with larger follicles using either mm (ROC’s AUC = 0.59; P = 0.01) or Z values (ROC’s AUC = 0.57; P = 0.01). The use of follicle diameter as a feature to distinguish between fertilized oocytes that would ultimately become blastocysts versus those that would not become blastocysts resulted in an enrichment for blastocyst formation from 20 to 40%. Of the 94 quality blastocysts, 51 were determined by next generation sequencing (NGS) to be euploid.Although oocyte maturity and the incidence of blastocyst formation were associated with follicle size, the incidence of euploidy among biopsied blastocysts was not. Follicles measured by two different methods (mm or Z values) led to predominantly the same conclusions.

LIMITATIONS, REASONS FOR CAUTION

This study investigated the relationship between follicle size and measures of oocyte/embryo quality when donors were treated similarly. Therefore, this study does not investigate the effects of triggering and retrieving oocytes when the follicle cohorts are of different sizes or lead follicles are of different sizes. Although no association was found between follicle size and euploid blastocysts, the fact that blastocyst ploidy is not entirely dependent upon oocyte ploidy (e.g. aneuploidies derived from mitotic errors or from the fertilizing sperm) makes it difficult to infer the relationship between follicle diameter and oocyte ploidy.

WIDER IMPLICATIONS OF THE FINDINGS

It is confirmed that follicle diameter is predictive of oocyte maturity. However, once oocyte maturity is known, the diameter of the follicle from which the oocyte was retrieved is not instructive. Embryos generated through fertilization and development of the mature oocytes from any observed follicle diameter were equally likely to become euploid blastocysts.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by ReproART: Georgian American Center for Reproductive Medicine. None of the authors declare any actual conflicts of interest. D.H.M. received compensation from ReproART, Biogenetics Corporation and the Sperm and Embryo Bank of New York and honoraria and travel funding from Ferring Pharmaceuticals and from Granata Bio. S.M. received compensation from Cooper Genomics and an honorarium and travel funding from Ferring Pharmaceuticals. L.C. is the founder of LTD Ovamedi, the organization that represents Cooper Genomics in Georgia, and received travel funding from the European Society for Human Reproduction and Embryology.

TRIAL REGISTRATION NUMBER

N/A.

Immature oocyte incidence: Contributing factors and effects on mature sibling oocytes in intracytoplasmic sperm injection cycles

Objective

The aim of this study was to investigate which factors contribute to the incidence of immature oocytes (germinal vesicle -GV- and metaphase I -MI-) and how they impact the intracytoplasmic sperm injection (ICSI) outcomes of sibling mature oocytes.

Methods

Data from 3,920 cycles performed from June/2010 to August/2016 in a private university-affiliated IVF center were evaluated for the influence of controlled ovarian stimulation protocol (COS) on immature oocytes incidence and its effects on ICSI outcomes.

Results

MI (p=0.004) and GV (p=0.029) number were negatively correlated with gonadotropin dose. Patients stimulated by rFSH had increased GV/oocyte rate in both GnRH agonists (p<0.001) and antagonist (p=0.042) protocols, in comparison to rFSH associated with rLH protocol. MI and GV/oocyte rates were negatively correlated to fertilization (p<0.001), high-quality embryo on da p<0.001; GV/oocyte p=0.033) and pregnancy (MI/oocyte p=0.002; GV/oocyte p=0.013) rates. Cycles above a 10.5% MI/oocyte cut-off were correlated to higher response to ovarian stimulation, poor embryo development and almost two times lower pregnancy rate. Immature oocyte incidence is affected by COS and impacts on ICSI outcomes.

Conclusion

Our evidence suggests that oocytes derived from a cohort with high incidence of maturation fail may have detrimental clinical outcomes.

High rates of aneuploidy, mosaicism and abnormal morphokinetic development in cases with low sperm concentration

Purpose

The aim of our study was to evaluate the impact of severe male infertility (SMF) on the chromosomal status of embryos and any possible correlation between chromosomal status and embryo morphokinetics in younger women using data obtained from comprehensive preimplantation genetic tests.

Methods

The trial was conducted in an ART and Reproductive Genetics Centre between 2011 and 2018. A total of 326 cycles in cases with SMF where the female partner’s age was ≤ 35 years were evaluated. SMF is defined as sperm concentration below 5 mil/ml (million per milliliter) and divided into three subgroups according to sperm concentrations: 1–5 mil/ml, < 1mil/ml and testicular sperm. The control group of 190 cycles had normal sperm parameters.

Results

Significantly lower chromosomal euploidy rates were found in the testicular sperm group compared with the normal sperm controls when the female age was ≤ 35 years. In SMF, statistically significantly affected chromosomes were 2, 10, 11, 17, 21 and sex chromosomes. The mosaicism and abnormal morphokinetic development rates were higher in the SMF group than in control group, and this difference was significant when testicular sperm was used.

Conclusion

Lower euploidy rates, higher mosaicism rates and a higher incidence of abnormal morphokinetic development were observed in cases with testicular sperm with female partners ≤ 35 years compared with normal sperm controls. These findings suggest that PGT-A may be advisable in severe male infertility cases. Furthermore, the correlation between morphokinetics and chromosomal status was greatly reduced or absent in these most severe forms of male infertility, thus the need for new morphokinetic models.

Electronic supplementary material

The online version of this article (10.1007/s10815-019-01673-w) contains supplementary material, which is available to authorized users.

Morphokinetic characteristics of embryos originating from extremely small follicles: A prospective study

OBJECTIVE

To investigate the developmental potential of oocytes and embryos derived from extremely small follicles (<10 mm) in comparison to those originated in larger follicles.

STUDY DESIGN

A prospective study, undertaken in a university affiliated single center tertiary hospital. The study included 98 patients undergoing infertility treatments. On the day of ovum pickup (OPU) follicles were counted and measured. Aspiration of follicles larger and smaller than 10 mm was undertaken separately and the development of embryos originating from oocytes from these follicles was followed up using different wells for each embryo. There was no low limit of size for aspiration. Each oocyte retrieved was marked for its origin and numbered for further follow up. We recorded: Oocytes retrieved, maturation stage, fertilization rate, cleavage rate, morphokinetic parameters, embryo transfers, embryo freezing, oocyte freezing and biopsy rate for preimplantation genetic diagnosis (PGD). Quality was evaluated by the morphokinetic parameters of the embryos developed using time-lapse imaging technology. Day 3 KIDScore was calculated to all embryos.

RESULTS

Small follicles compared to large follicles displayed lower recovery rate (45% vs. 74%, P < 0.0001), fewer matured oocytes (37.5% vs. 61.7%, P < 0.0001), higher rates of GV oocytes (20.7% vs., 3.7%, P < 0.0001), and lower fertilization rate (43.7% vs. 63.3%, P < 0.0001. However, morphokinetic variables were similar between embryos that originated from either small or large follicles. Median KIDscores were identical for embryos from small or large follicle origin.

CONCLUSIONS

Embryos originated from small follicles were not different than embryos from larger follicles, as assessed by morphokinetic parameters in time lapse system. In view of our findings, physicians should bear in mind that small follicle aspiration might yield good quality embryos.

Is there a correlation between follicle size and gene expression in cumulus cells and is gene expression an indicator of embryo development?

BACKGROUND

In an article published in 2017, we discussed the results of the first part of our study into the morphokinetic development of embryos in relation to follicle diameter and homogeneity of follicular development. Our findings showed that embryos coming from small follicles in heterogeneous cycles had significantly higher rates of arrest or failure to reach blastocyst than embryos coming from large follicles in homogenous cycles. The aim of this further study was to investigate the relationship between follicular size and gene expression of cumulus cells (CCs) and evaluate whether gene expression could be an indicator of embryo development.

METHODS

This study was based on 2495 COCs from 184 patients. CC expressions of five genes (TNFAIP6, PTGS2, HAS2, PTX3 and GDF9) were studied by generalized linear mixed models (GLMMs) regarding follicular size. CC expressions were then separately analysed regarding patient-specific variables (age, BMI, AMH and follicular size) in relation to embryos reaching blastocyst (eRB) or top or good quality blastocysts (TQ + GQ) using GLMMs with logit link.

RESULTS

Follicular size significantly correlated with the potential of an oocyte to develop into a blastocyst: oocytes developing from large follicles were more than twice as likely to develop into an eRB than oocytes from small follicles (p < 0.001). Gene expression of HAS2 and GDF9 correlated with blastocyst quality when separately evaluated with follicular size and the patient specific variables of age, BMI and AMH. However, no such correlation was found in other gene expressions studied.

CONCLUSIONS

Our findings suggest that differences in the expression of genes studied could be related to follicular size rather than to embryo quality. Although gene expression of HAS2 and GDF9 correlated with blastocyst quality, the only variable correlating with eRB and TQ and GQ blastocysts for each of these five models was follicular size.

TRIAL REGISTRATION

This prospective cohort study was registered at clinicaltrials.gov (NCT02230449).