Impact of ovarian reserve markers on oocyte maturity and embryological outcomes in in vitro fertilization/intracytoplasmic sperm injection cycles: A retrospective cohort study
Article information
Abstract
Objective
Despite advances in assisted reproductive technologies, predicting outcomes of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) remains difficult. Hormonal status, oocyte maturity, and ovarian reserve contribute to treatment variability. This study examined correlations among demographic, endocrine, and embryological parameters in women undergoing IVF and ICSI whose partners had normal semen profiles, and evaluated the effect of follicle-stimulating hormone (FSH) levels on outcomes.
Methods
A retrospective analysis was performed on 488 women aged 18 to 45 years who underwent IVF and ICSI between 2022 and 2024. Data included age, body mass index (BMI), infertility duration, and levels of FSH, luteinizing hormone, anti-Müllerian hormone (AMH), thyroid-stimulating hormone, and fasting blood sugar. Embryological variables were oocyte yield, maturity stages (germinal vesicle, metaphase I, and metaphase II [MII]), and embryo count. Pearson correlations and the Kruskal–Wallis test were used to compare groups stratified by FSH (<10, 10–20, >20 mIU/mL).
Results
BMI and infertility duration showed weak correlations with embryological outcomes. AMH correlated positively with embryo count (r=0.29, p<0.01). MII oocytes correlated strongly with oocyte yield (r=0.90, p<0.01) and moderately with embryo count (r=0.46, p<0.01). Women with FSH <10 mIU/mL had significantly higher oocyte yield, MII oocyte numbers, and embryo counts than those with FSH ≥10 mIU/mL (p<0.001).
Conclusion
Lower FSH and higher AMH are associated with better oocyte maturity and embryo yield. These markers may support individualized stimulation strategies to improve IVF and ICSI outcomes.
Introduction
Infertility affects approximately 10% to 15% of couples worldwide, with female factors accounting for nearly half of all cases [1]. In vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) have transformed infertility management, providing hope to couples who might otherwise remain childless [2]. Despite ongoing technological progress, the success of assisted reproductive technologies (ART) continues to depend largely on patient-specific factors, including age, body mass index (BMI), ovarian reserve, and hormonal profiles [3-5].
Assessment of ovarian reserve is a critical aspect of predicting ovarian responsiveness to stimulation and the likelihood of achieving pregnancy through ART. Commonly used markers of ovarian reserve include follicle-stimulating hormone (FSH), anti-Müllerian hormone (AMH), and antral follicle count (AFC) [6-8]. Elevated baseline FSH has traditionally been linked to diminished ovarian reserve and poorer IVF outcomes, whereas AMH has emerged as a more stable and predictive marker of ovarian response [9,10]. Nonetheless, the interactions between demographic factors, hormonal parameters, and embryological outcomes remain complex and require further investigation.
Numerous studies have explored the relationships among oocyte yield, oocyte maturity, and embryo development in the context of ART outcomes [11-13]. It is well established that both the quantity and quality of retrieved oocytes—particularly the proportion of mature metaphase II (MII) oocytes—are key determinants of fertilization and subsequent embryo viability [14]. Furthermore, variations in oocyte maturity stages, including germinal vesicle (GV) and metaphase I (MI) stages, offer valuable insights into ovarian competence and overall reproductive potential [15].
Given the multifactorial nature of IVF/ICSI outcomes, a comprehensive understanding of how demographic and endocrine factors interact with embryological parameters is essential for optimizing treatment strategies and improving patient counseling. In particular, examining the role of baseline FSH in influencing oocyte retrieval, maturation, and embryogenesis is crucial, especially in cases of non-male factor infertility, where female parameters predominantly determine success.
In this study, we sought to evaluate correlations among patient demographics, hormonal profiles, and embryological outcomes in women undergoing IVF/ICSI with partners who have normal semen parameters. We further compared IVF/ICSI outcomes across different FSH categories to clarify the impact of ovarian reserve on treatment success. By identifying key predictors of oocyte competence and embryo development, our findings aim to contribute to the advancement of more individualized and effective ART protocols.
Methods
1. Study design and participants
This retrospective cohort study included 488 women who underwent IVF or ICSI between 2022 and 2024 at Hazrate Zainab Hospital, affiliated with Shiraz University of Medical Sciences (SUMS). All participants had partners with normal semen parameters according to World Health Organization criteria, thereby excluding male factor infertility from the study.
Inclusion criteria were: women aged 18 to 45 years, candidates for IVF/ICSI, and the availability of complete clinical and laboratory data. Women with uterine abnormalities, known chromosomal abnormalities, autoimmune diseases, or male partner infertility factors were excluded. Ethical approval was obtained from the Medical Ethics Committee of SUMS under reference number IR.SUMS.REC.1401.318. Informed consent was obtained from all participants.
2. Data collection
Demographic and clinical information were extracted from the infertility registry system (https://mdreg.mums.ac.ir/index.php). Data collected included patient age, BMI, age at menarche, duration of primary and secondary infertility, and underlying medical conditions (e.g., hypothyroidism). Baseline hormonal profiles measured included serum levels of FSH, luteinizing hormone (LH), AMH, thyroid-stimulating hormone (TSH), and fasting blood sugar (FBS). IVF/ICSI outcomes recorded comprised: number of oocytes retrieved; number of GV-stage, MI-stage, and MII-stage oocytes; and the number of embryos generated.
3. Laboratory assessments
Baseline hormone levels were assessed on day 2 or 3 of the menstrual cycle using standard immunoassay techniques. Ovarian stimulation protocols were standardized per institutional guidelines, utilizing either gonadotropin-releasing hormone agonists or antagonists. Oocyte retrieval was performed 36 hours after administration of the human chorionic gonadotropin trigger, and oocytes were classified according to maturity stage (GV, MI, and MII). Fertilization was achieved using either IVF or ICSI, following established laboratory procedures.
4. Statistical analysis
Descriptive statistics were calculated for all demographic, clinical, and hormonal variables. Continuous data are presented as mean±standard deviation, while categorical variables are presented as percentages. Pearson correlation coefficients were calculated to assess associations between demographic parameters, hormonal profiles, and embryological outcomes. The strength of correlations was interpreted as follows: |r|<0.3 (weak), 0.3≤|r|<0.7 (moderate), and |r|≥0.7 (strong). A heatmap was generated to visually display the correlation matrix.
Comparisons of IVF/ICSI outcomes across different FSH categories (<10, 10–20, >20 mIU/mL) were conducted using the Kruskal–Wallis test, a nonparametric alternative to one-way analysis of variance. Post hoc pairwise comparisons were performed using the Mann–Whitney U test. Statistical significance was defined as p<0.05. All analyses were performed using SPSS ver. 25.0 (IBM Co.).
Results
1. Patient demographics and clinical characteristics
A total of 488 women undergoing IVF/ICSI treatment were included in this study. All participants had partners with normal sperm parameters; therefore, male factor infertility was not considered among the study variables. Patient demographic and hormonal data are summarized in Table 1. The mean age of participants was 34.41±10.49 years, and the mean BMI was 25.95±4.49 kg/m². The average age at menarche was 13.11±1.86 years. The mean duration of primary infertility was 6.05±4.48 years, while the mean duration of secondary infertility was 5.17±3.65 years. Endocrine assessment revealed a mean FSH level of 10.35±12.33 mIU/mL, a mean LH level of 6.65±7.77 mIU/mL, and a mean AMH level of 4.07±3.44 ng/mL. Metabolic and thyroid function testing showed a mean FBS of 93.02±10.06 mg/dL and a mean TSH level of 2.69±2.02 mIU/L.
Descriptive statistics of the study population
2. Correlations among demographic, hormonal, and embryological parameters
To examine relationships among demographic characteristics, hormonal profiles, and embryological outcomes, a Pearson correlation matrix was generated and visualized as a heatmap (Figure 1).
Correlation matrix between demographic characteristics, hormonal profiles, and in vitro fertilization/intracytoplasmic sperm injection outcomes. The heatmap illustrates the Pearson correlation coefficients among demographic parameters, hormonal profiles, and embryological outcomes. Color intensity reflects the strength and direction of correlations (blue: negative; red: positive). AMH, anti-Müllerian hormone; FSH, follicle-stimulating hormone; BMI, body mass index; LH, luteinizing hormone; FBS, fasting blood sugar; TSH, thyroid-stimulating hormone; GV, germinal vesicle; MI, metaphase I; MII, metaphase II.
3. Association of demographic factors with IVF/ICSI outcomes
Age, age at menarche, and BMI each demonstrated weak and non-significant correlations with the number of embryos generated: age (r=–0.064), age at menarche (r=–0.031), and BMI (r=–0.058). A modest positive correlation was observed between the duration of primary infertility and the number of embryos (r=0.117, p<0.05), suggesting that a longer duration of infertility may be associated with improved embryological outcomes. Conversely, secondary infertility was negatively correlated with embryo number (r=–0.185), though this association was not statistically significant.
4. Associations of hormonal parameters with embryological outcomes
Among the hormonal markers, AMH showed a significant positive correlation with the number of embryos generated (r=0.292, p<0.01), reinforcing its predictive value for ovarian response. FSH, LH, FBS, and TSH levels did not demonstrate significant correlations with embryo number.
5. Correlations between oocyte maturity stages and embryo yield
The number of oocytes retrieved showed a strong positive correlation with the number of embryos generated (r=0.488, p<0.01), highlighting the importance of oocyte quantity. The number of retrieved oocytes also strongly correlated with oocyte maturity stages as follows: GV-stage oocytes (r=0.471, p<0.01); MI-stage oocytes (r=0.440, p<0.01), and MII-stage oocytes (r=0.901, p<0.01).
The particularly strong correlation between MII-stage oocytes and total oocytes retrieved emphasizes the critical importance of mature oocyte collection for optimizing IVF/ICSI outcomes. The number of MII-stage oocytes also exhibited a strong positive correlation with embryo number (r=0.458, p<0.01).
6. Summary of correlation findings
Overall, demographic factors such as age and BMI had minimal influence on embryological outcomes. In contrast, markers of ovarian reserve, specifically AMH levels and the number of mature (MII-stage) oocytes, emerged as strong predictors of embryo development and IVF/ICSI success (Table 2).
Correlation analysis among demographic, hormonal, and embryological parameters
7. Comparison of IVF/ICSI outcomes across FSH groups
IVF/ICSI outcomes were compared across three FSH categories: <10, 10–20, and >20 mIU/mL (Table 3, Figure 2). Kruskal–Wallis analysis demonstrated significant differences among the groups for the number of retrieved oocytes (p<0.001), MII-stage oocytes (p<0.001), GV-stage oocytes (p=0.018), and number of embryos generated (p<0.001). No significant difference was observed for MI-stage oocytes (p=0.467).
Comparison of IVF/ICSI outcomes across FSH groups
Comparison of in vitro fertilization/intracytoplasmic sperm injection outcomes across follicle-stimulating hormone (FSH) groups. (A) Retrieved oocytes, (B) germinal vesicle (GV)-stage oocytes, (C) metaphase I (MI)-stage oocytes, (D) metaphase II (MII)-stage oocytes, and (E) number of embryos were compared among patients with FSH <10, 10–20, and >20 mIU/mL. Error bars represent standard deviations. Statistical significance between groups was determined using the Mann–Whitney U test. Statistical significance was evaluated using the Mann–Whitney U test (p<0.05). ns, not significant. a)p<0.01; b)p<0.001.
Post hoc pairwise comparisons showed that patients with FSH <10 mIU/mL had significantly higher numbers of retrieved oocytes, mature MII-stage oocytes, and embryos compared to those with FSH 10–20 mIU/mL (all p<0.001). No statistically significant differences were identified between the FSH >20 and 10–20 mIU/mL groups for any of the parameters assessed. Overall, these findings indicate that patients with FSH levels below 10 mIU/mL exhibit superior oocyte retrieval, maturation, and embryogenesis compared to those with intermediate or elevated FSH levels.
Discussion
This study evaluated the correlations between demographic, hormonal, and embryological parameters and assessed IVF/ICSI outcomes across different FSH groups in a large cohort of women with partners exhibiting normal semen parameters. Our findings demonstrated that lower FSH levels (<10 mIU/mL) were associated with significantly higher numbers of retrieved oocytes, mature MII-stage oocytes, and embryos compared to both intermediate (10–20 mIU/mL) and elevated (>20 mIU/mL) FSH groups.
The observed positive correlation between AMH levels and embryo numbers supports the existing literature emphasizing AMH as a reliable marker of ovarian reserve and a predictor of ovarian response [16,17]. Similarly, the strong correlation between the number of retrieved oocytes and MII-stage oocytes is consistent with previous studies highlighting the critical role of oocyte maturity in successful fertilization and embryo development [18,19]. However, although women with polycystic ovary syndrome (PCOS) often exhibit elevated AMH levels and a higher yield of oocytes, the developmental competence and fertilization potential of these oocytes may be impaired, resulting in suboptimal IVF/ICSI outcomes [20]. This paradox underscores the need for cautious interpretation of AMH levels in PCOS populations and highlights the importance of assessing both oocyte quantity and quality when predicting treatment success [21,22]. These findings reinforce the concept that oocyte competence, rather than oocyte quantity alone, is pivotal in determining IVF success. Notably, the strong association between MII-stage oocytes and embryo numbers further underscores the importance of retrieving mature oocytes for maximizing embryo development potential.
Comparative analysis across FSH groups revealed that women with FSH <10 mIU/mL had superior IVF outcomes, which is consistent with prior research indicating that lower baseline FSH levels are associated with better ovarian response and higher pregnancy rates [23,24]. Elevated FSH levels, which are typically indicative of diminished ovarian reserve, have been linked to poorer IVF outcomes due to reduced follicular recruitment and impaired oocyte quality [25,26].
Regarding oocyte maturity stages, our finding that GV-stage oocyte numbers differed significantly among FSH groups suggests that baseline ovarian reserve influences not only oocyte quantity but also developmental competence. This observation is in line with previous reports indicating that women with diminished ovarian reserve exhibit a higher proportion of immature oocytes [27]. Therefore, evaluating oocyte maturity profiles in addition to quantity could enhance individualized prognostication for IVF outcomes.
The clinical implications of these findings are significant. Baseline FSH levels should be carefully considered when counseling patients regarding IVF prognosis. Women with FSH levels <10 mIU/mL may expect more favorable outcomes, whereas those with elevated FSH should be counseled about potentially reduced oocyte yields and embryo numbers. Tailored stimulation protocols based on ovarian reserve markers could optimize outcomes and improve patient expectations [28,29]. Moreover, integrating additional markers such as AMH and AFC alongside FSH may provide a more comprehensive assessment of reproductive potential.
This study’s strengths include its large sample size, strict inclusion of non-male factor infertility cases, and comprehensive evaluation of multiple embryological outcomes. However, several limitations should be acknowledged. The retrospective design limits causal inference, and variations in stimulation protocols were not controlled. Furthermore, clinical pregnancy and live birth outcomes, which are key benchmarks for evaluating ART success, should be included in future prospective investigations to validate and extend our findings.
In conclusion, this study demonstrated that lower baseline FSH levels are significantly associated with improved oocyte retrieval, oocyte maturity, and embryo development outcomes in women undergoing IVF/ICSI treatment. Among the hormonal and demographic factors evaluated, AMH levels and the number of mature MII-stage oocytes emerged as the strongest predictors of successful embryological outcomes. Our findings emphasize the critical role of ovarian reserve assessment, particularly baseline FSH and AMH measurements, in guiding clinical decision-making and patient counseling. These results support the need for individualized ovarian stimulation protocols tailored to each patient’s ovarian reserve status to optimize IVF/ICSI success rates. Further prospective studies evaluating embryo quality and clinical pregnancy outcomes are warranted to validate and expand upon these observations.
Notes
Conflict of interest
No potential conflict of interest relevant to this article was reported.
Author contributions
Conceptualization: SS (Soudabeh Sabetian), BNJ. Methodology: SS (Soudabeh Sabetian), FD, ZE. Formal analysis: SS (Soudabeh Sabetian). Data curation: FD, ZE. Funding acquisition: SS (Soudabeh Sabetian). Project administration: SS. (Soudabeh Sabetian), BNJ. Visualization: SS (Soudabeh Sabetian), BNJ, SA (Sareh Ashourzadeh), SS (Somayyeh Safari), SA (Sanaz Alaee). Software: SS (Soudabeh Sabetian). Validation: SS (Soudabeh Sabetian), FD, ZE, BNJ, SA (Sareh Ashourzadeh), SS (Somayyeh Safari), SA (Sanaz Alaee). Investigation: SS (Soudabeh Sabetian), FD, ZE, BNJ. Supervision: SS (Soudabeh Sabetian). Writing-original draft: SS (Soudabeh Sabetian), BNJ, SA (Sareh Ashourzadeh), SS (Somayyeh Safari), SA (Sanaz Alaee).