Glowing oocytes within a woman's silhouette, symbolizing ovarian reserve and IVF success.

Decoding Your Ovarian Response: How Many Oocytes Are Enough?

Lena Voss in Health & Wellness August 2025 • 4 min read.

"Navigating the complexities of IVF: A clear definition of poor ovarian response can improve treatment outcomes and patient expectations."

For couples navigating infertility, in vitro fertilization (IVF) offers a beacon of hope. A crucial step in IVF is retrieving healthy oocytes (eggs). While mild ovarian stimulation is sometimes used, conventional stimulation aims for at least eight oocytes. However, when only a few oocytes are retrieved, it can lead to total fertilization failure or a lack of transferable embryos, a situation known as poor ovarian response (POR). This can be emotionally and financially taxing for individuals and couples.

Defining POR has been a challenge. A 2011 consensus from the European Society of Human Reproduction and Embryology (ESHRE) proposed the 'Bologna criteria,' but these have faced criticism for being too broad and lacking a solid scientific basis. The core issue is determining the optimal number of oocytes that predict successful IVF outcomes.

This article explores recent research aimed at refining the definition of POR using statistical and outcome-based approaches. We'll delve into what number of oocytes is truly 'appropriate' and how this new understanding can improve IVF success rates and patient care.

Defining Poor Ovarian Response: Beyond the Bologna Criteria

Glowing oocytes within a woman's silhouette, symbolizing ovarian reserve and IVF success.

The original research aimed to develop a more precise definition of POR by analyzing data from 176 IVF cycles. The study considered both statistical distributions of oocyte numbers and the resulting IVF outcomes (pregnancy rates) to determine optimal cut-off points.

Here's how the research team approached the challenge:

Statistical Analysis: They examined the distribution of total and mature oocytes retrieved during IVF cycles to establish percentile cut-offs.
Outcome Prediction: They used ROC curve analysis to determine which oocyte numbers (total and mature) best predicted IVF pregnancy success.
Defining POR: They considered the incidence of POR and the predictive power of different oocyte number cut-offs to arrive at a reasonable and statistically supported definition.

The researchers discovered that the 25th percentile for oocyte retrieval corresponded to ≤2 total oocytes and ≤1 mature oocyte. Outcome prediction analysis revealed that retrieving >5 total oocytes and >1 mature oocyte were significant for IVF success. Considering these results, they defined POR as retrieval of ≤2 total oocytes or ≤1 mature oocyte.

A New Definition and Its Implications

Based on their findings, the researchers proposed a new, simple definition of POR: a total oocyte retrieval of ≤2 or a mature oocyte retrieval of ≤1 in a previous cycle, or a serum Anti-Müllerian Hormone (AMH) level of ≤0.76 ng/mL. AMH is a hormone produced by cells in ovarian follicles, and is often used to assess a woman's ovarian reserve.

Importantly, this new definition demonstrated similar predictive performance to the Bologna criteria but is grounded in statistical analysis and outcome prediction. Using AMH levels alongside oocyte retrieval numbers provided a more refined and practical approach to identifying women with POR.

This refined definition of POR offers several potential benefits: <ul><li>Improved Prediction: More accurately identifying women likely to experience poor response.</li><li>Personalized Treatment: Tailoring IVF protocols based on individual ovarian reserve.</li><li>Realistic Expectations: Providing couples with more accurate prognoses and counseling.</li></ul> While further research is always valuable, this study represents a significant step towards a more evidence-based and patient-centered approach to IVF treatment.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.3349/ymj.2015.56.2.482, Alternate LINK

Title: What Number Of Oocytes Is Appropriate For Defining Poor Ovarian Response?

Subject: General Medicine

Journal: Yonsei Medical Journal

Publisher: Yonsei University College of Medicine

Authors: Seul Ki Kim, Jung Ryeol Lee, Byung Chul Jee, Chang Suk Suh, Seok Hyun Kim

Published: 2015-01-01

Everything You Need To Know

What is Poor Ovarian Response (POR), and why is it significant in IVF?

In the context of in vitro fertilization (IVF), Poor Ovarian Response (POR) refers to a situation where a woman's ovaries do not produce enough oocytes (eggs) in response to ovarian stimulation. The retrieved oocyte count is crucial for IVF success. POR is typically defined as retrieving a low number of oocytes, specifically ≤2 total oocytes or ≤1 mature oocyte. This can lead to fertilization failure or an insufficient number of embryos for transfer, significantly impacting the chances of a successful pregnancy.

Why is it important to define Poor Ovarian Response (POR)?

Defining Poor Ovarian Response (POR) is important because it directly influences the management of IVF treatments and patient expectations. An accurate definition allows clinicians to better predict the likelihood of success, tailor treatment plans to individual patient needs, and adjust expectations regarding the potential outcomes of IVF cycles. The Bologna criteria, though once widely used, have faced criticism for being too broad. Newer definitions, like the one proposed based on a recent study, refine this concept for more precise patient care.

How did researchers arrive at a new definition for Poor Ovarian Response (POR)?

The study employed a multi-faceted approach. First, the researchers conducted a statistical analysis of the distribution of total and mature oocytes retrieved during IVF cycles. They established percentile cut-offs to define the normal range. Next, they used ROC curve analysis to determine how the number of oocytes, both total and mature, correlated with IVF pregnancy success. By considering statistical distributions and predictive power, they could define POR based on cut-off points of retrieved oocytes.

What is the new definition of Poor Ovarian Response (POR) based on the recent research?

The new definition proposed, based on the research, is a total oocyte retrieval of ≤2 or a mature oocyte retrieval of ≤1 in a previous cycle, or a serum Anti-Müllerian Hormone (AMH) level of ≤0.76 ng/mL. This definition is designed to be more precise than the previous Bologna criteria. The use of AMH, a hormone indicating ovarian reserve, adds another dimension to this assessment, providing a more comprehensive understanding of a woman's ovarian potential.

What is the role of Anti-Müllerian Hormone (AMH) in assessing ovarian response?

Anti-Müllerian Hormone (AMH) is a hormone produced by cells in the ovarian follicles and is used to assess a woman's ovarian reserve, or the quantity of eggs remaining in the ovaries. AMH levels help to predict how a woman's ovaries will respond to stimulation during IVF. A lower AMH level (≤0.76 ng/mL, in the context of the new POR definition) may indicate a reduced ovarian reserve and a higher likelihood of POR. Incorporating AMH in the definition improves the ability to assess the potential for success in IVF.