Oocyte maturity, oocyte fertilization and cleavage-stage embryo morphology are better in natural compared with high-dose gonadotrophin stimulated IVF cycles

Oocyte and zygote development potential in minimal stimulation, natural cycle and conventionally stimulated IVF: an international multi-centre retrospective cohort study

PURPOSE

The aim of this research is to assess the development potential of oocytes and zygotes obtained from Natural cycle IVF (NC-IVF), different minimal stimulation IVF (Min stim-IVF) and conventionally stimulated IVF (cIVF) treatment protocols.

METHODS

International multi-centre retrospective cohort study including 1483 NC-IVF, 1208 Min stim-IVF, and 1892 cIVF cycles performed in 8 IVF centres between 01.2022 and 03.2023. The five Min stim-IVF protocols analysed included low dose clomiphene citrate, aromatase inhibitors, low dose (≤ 100 IU) gonadotropins, each alone or in combination. For each IVF protocol, we assessed and modelled the transition probabilities of (i) each observed oocyte developing into a zygote, (ii) each observed zygote developing into a gestational sac and (iii) each observed zygote developing into a live birth.

RESULTS

All modelled transition probabilities were found to be maximal in NC-IVF, minimal in cIVF with Min stim-IVF in between. The probability of transition from oocyte to zygote was 0.72 for NC-IVF, 0.56 to 0.65 for Min stim-IVF protocols and 0.54 for cIVF. The probability of transition from zygote to gestational sac was 0.21 for NC-IVF, 0.14 to 0.19 for Min stim-IVF and 0.09 for cIVF protocols and from zygote to live birth 0.16 for NC-IVF, 0.09 to 0.16 for Min stim-IVF and 0.06 for cIVF protocols.

CONCLUSIONS

The transition probabilities of oocytes and zygotes appears to be higher in NC-IVF, followed by Min stim-IVF and then cIVF, suggesting that increasing dosages of gonadotropins might have a negative effect on oocyte/zygote development potential.

TRIAL REGISTRATION

Clinicaltrial.gov: NCT05125497. Registration date 03.11.2021.

Granulosa cell transcription is similarly impacted by superovulation and aging and predicts early embryonic trajectories

In vitro fertilization efficiency is limited in part because a fraction of retrieved oocytes fails to fertilize. Accurately evaluating their quality could significantly improve in vitro fertilization efficiency, which would require better understanding how their maturation may be disrupted. Here, we quantitatively investigate the interplay between superovulation and aging in mouse oocytes and their paired granulosa cells using a newly adapted experimental methodology. We test the hypothesis that superovulation disrupts oocyte maturation, revealing the key intercellular communication pathways dysregulated at the transcriptional level by forced hormonal stimulation. We further demonstrate that granulosa cell transcriptional markers can prospectively predict an associated oocyte's early developmental potential. By using naturally ovulated old mice as a non-stimulated reference, we show that aging and superovulation dysregulate similar genes and interact with each other. By comparing mice and human transcriptional responses of granulosa cells, we find that age-related dysregulation of hormonal responses and cell cycle pathways are shared, though substantial divergence exists in other pathways.

Oocyte retrieval of few follicles does not require analgesia: a large-scale multicentre pain analysis

RESEARCH QUESTION

What is the pain intensity of oocyte retrieval (OCR) without anaesthesia and analgesia in women with a low or medium number of follicles?

DESIGN

Multicentre observational study analysing IVF cycles without anaesthesia and analgesia in seven IVF centres in Germany and Switzerland between January 2022 and March 2023. In total, 2290 cycles of natural cycle IVF or minimal stimulation IVF from 1039 patients were recorded. Pain score was assessed using a VAS graded 0 to 10. A descriptive analysis was conducted, followed by a statistical evaluation using a linear mixed model to analyse the effect on the pain score of the number of oocytes retrieved and the number of repeated IVF cycles.

RESULTS

The number of oocytes retrieved varied from 0 to 16 (IQR 1-2). Pain score varied from 0 to 10, with a median pain score of 3.0 (IQR 2-4), defined as 'mild' pain. Compared with a reference value of aspirations with one oocyte, the pain score increased slightly by 0.5 points if no oocyte was retrieved, by 0.42 points if two to five oocytes were retrieved and by 1.14 points if six or more oocytes were retrieved, all with little clinical relevance. Pain decreased slightly with repeated aspirations (-0.05 points per cycle) (P = 0.028). The complication rate requiring hospitalization per aspiration was less than 0.1%.

CONCLUSION

Pain intensity during OCR of one or few follicles is mild. Therefore, OCR can be offered without anaesthesia and analgesia to reduce aspiration time and cost.

Ovarian stimulation protocols: impact on oocyte and endometrial quality and function

Ovarian stimulation (OS) truly is an art. There exists a myriad of protocols used to achieve the same goal: stimulating the ovaries to produce more than one mature oocyte to improve the chance of a live birth. However, considerable debate remains as to whether OS impacts oocyte and endometrial quality to affect in vitro fertilization outcomes. Although "more is better" has long been considered the best approach for oocyte retrieval, this review challenges that notion by examining the influence of stimulation on oocyte quality. Likewise, improved outcomes after frozen blastocyst transfer suggest that OS perturbs endometrial preparation and/or receptivity, although correlating changes with implantation success remains a challenge. Therefore, the focus of this review is to summarize our current understanding of perturbations in human oocyte quality and endometrial function induced by exogenous hormone administration. We highlight the need for further research to identify more appropriate markers of oocyte developmental competence as well as those that define the roles of the endometrium in the success of assisted reproductive technology.

Exploring gonadotropin dosing effects on MII oocyte retrieval in ovarian stimulation

PURPOSE

Ovarian stimulation with gonadotropins is crucial for obtaining mature oocytes for in vitro fertilization (IVF). Determining the optimal gonadotropin dosage is essential for maximizing its effectiveness. Our study aimed to develop a machine learning (ML) model to predict oocyte counts in IVF patients and retrospectively analyze whether higher gonadotropin doses improve ovarian stimulation outcomes.

METHODS

We analyzed the data from 9598 ovarian stimulations. An ML model was employed to predict the number of mature metaphase II (MII) oocytes based on clinical parameters. These predictions were compared with the actual counts of retrieved MII oocytes at different gonadotropin dosages.

RESULTS

The ML model provided precise predictions of MII counts, with the AMH and AFC being the most important, and the previous stimulation outcome and age, the less important features for the prediction. Our findings revealed that increasing gonadotropin dosage did not result in a higher number of retrieved MII oocytes. Specifically, for patients predicted to produce 4-8 MII oocytes, a decline in oocyte count was observed as gonadotropin dosage increased. Patients with low (1-3) and high (9-12) MII predictions achieved the best results when administered a daily dose of 225 IU; lower and higher doses proved to be less effective.

CONCLUSIONS

Our study suggests that high gonadotropin doses do not enhance MII oocyte retrieval. Our ML model can offer clinicians a novel tool for the precise prediction of MII to guide gonadotropin dosing.

Gonadotropin elevation is ootoxic to ovulatory oocytes and inhibits oocyte maturation, and activin decoy receptor ActRIIB:Fc therapeutically restores maturation

BACKGROUND

Elevated FSH often occurs in women of advanced maternal age (AMA, age ≥ 35) and in infertility patients undergoing controlled ovarian stimulation (COS). There is controversy on whether high endogenous FSH contributes to infertility and whether high exogenous FSH adversely impacts patient pregnancy rates.

METHODS

The senescence-accelerated mouse-prone-8 (SAMP8) model of female reproductive aging was employed to assess the separate impacts of age and high FSH activity on the percentages (%) of viable and mature ovulated oocytes recovered after gonadotropin treatment. Young and midlife mice were treated with the FSH analog equine chorionic gonadotropin (eCG) to model both endogenous FSH elevation and exogenous FSH elevation. Previously we showed the activin inhibitor ActRIIB:Fc increases oocyte quality by preventing chromosome and spindle misalignments. Therefore, ActRIIB:Fc treatment was performed in an effort to increase % oocyte viability and % oocyte maturation.

RESULTS

The high FSH activity of eCG is ootoxic to ovulatory oocytes, with greater decreases in % viable oocytes in midlife than young mice. High FSH activity of eCG potently inhibits oocyte maturation, decreasing the % of mature oocytes to similar degrees in young and midlife mice. ActRIIB:Fc treatment does not prevent eCG ootoxicity, but it restores most oocyte maturation impeded by eCG.

CONCLUSIONS

FSH ootoxicity to ovulatory oocytes and FSH maturation inhibition pose a paradox given the well-known pro-growth and pro-maturation activities of FSH in the earlier stages of oocyte growth. We propose the FOOT Hypothesis ("FSH OoToxicity Hypothesis), that FSH ootoxicity to ovulatory oocytes comprises a new driver of infertility and low pregnancy success rates in DOR women attempting spontaneous pregnancy and in COS/IUI patients, especially AMA women. We speculate that endogenous FSH elevation also contributes to reduced fecundity in these DOR and COS/IUI patients. Restoration of oocyte maturation by ActRIB:Fc suggests that activin suppresses oocyte maturation in vivo. This contrasts with prior studies showing activin A promotes oocyte maturation in vitro. Improved oocyte maturation with agents that decrease endogenous activin activity with high specificity may have therapeutic benefit for COS/IVF patients, COS/IUI patients, and DOR patients attempting spontaneous pregnancies.