Oocyte Retrieval Strategies in In Vitro Fertilization
Summary
Oocyte retrieval is a cornerstone of in vitro fertilization (IVF), encompassing a sequence of steps from ovarian stimulation through to follicular aspiration. Controlled ovarian hyperstimulation (COH) seeks to recruit a cohort of mature follicles, balancing the maximisation of oocyte yield against the risk of ovarian hyperstimulation syndrome. Protocols vary according to the choice and timing of gonadotrophin-releasing hormone (GnRH) agonists or antagonists, the dose and type of follicle-stimulating hormone (FSH), and the use of human menopausal gonadotrophin. Triggering final oocyte maturation typically employs human chorionic gonadotrophin or a GnRH agonist to induce an endogenous luteinizing hormone surge. Ultrasound-guided transvaginal aspiration enables collection of cumulus–oocyte complexes, after which intracytoplasmic sperm injection or conventional insemination can proceed. Emerging strategies include individualised dosing guided by biomarkers of ovarian reserve, application of in vitro maturation for immature oocytes, and “freeze-all” approaches to mitigate adverse endometrial effects. Predictive tools and machine-learning models are increasingly used to forecast oocyte yield and tailor stimulation protocols to optimise safety and clinical outcomes.
Research from Nature Portfolio
Recent analysis of nearly 18 000 first IVF cycles demonstrated that both patient age and the number of oocytes retrieved act as independent predictors of cumulative live birth rate (CLBR). Women aged 35 or younger achieved over 60 percent CLBR when retrieving more than six oocytes, whereas those aged 38 and above required 14 or more oocytes for similar outcomes. Multivariate regression confirmed that each additional oocyte increased the odds of live birth independent of age, while older patients show a steeper threshold for oocyte yield. These findings inform protocol design, suggesting moderate stimulation for younger cohorts but more aggressive recruitment for those of advanced reproductive age to reach target CLBR.
Oocyte Retrieval Strategies in In Vitro Fertilization publication trend
The graph below shows the total number of articles in oocyte retrieval strategies in in vitro fertilization across all publications each year (not limited to Nature Index journals).
Technical terms
Controlled ovarian hyperstimulation (COH): Administration of exogenous gonadotrophins to stimulate the development of multiple ovarian follicles.
Antral follicle count (AFC): The number of small antral follicles visible on ultrasound, reflecting ovarian reserve.
Anti-Müllerian hormone (AMH): A hormone secreted by granulosa cells of pre-antral and small antral follicles, used as a marker of ovarian reserve.
In vitro maturation (IVM): Laboratory procedure in which immature oocytes are matured to metaphase II stage before fertilization.
Metaphase II (MII) oocyte: A mature oocyte that has completed the second meiotic division and is ready for fertilization.
References
- The association between the number of oocytes retrieved and cumulative live birth rate in different female age strata. Scientific Reports (2023).
- Predicting the number of oocytes retrieved from controlled ovarian hyperstimulation with machine learning. Human Reproduction (2023).
- Cut-off point of mature oocyte for routine clinical application of rescue IVM: a retrospective cohort study. Journal of Ovarian Research (2023).
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