Comparison of superstimulatory protocols with different doses of eCG on ovarian response and oocyte recovery by follicular aspiration in llamas (Lama glama)

The objective of this study was to evaluate the effect of three doses of equine chorionic gonadotropin (eCG) for ovarian superstimulation on ovarian response, follicular development and cumulus-oocyte complexes (COCs) collection in llamas. For this purpose, eighteen multiparous non-lactating adult (4-7 yo) female llamas with an average body condition of 2.8 (BCS 1-5) were submitted to a follicular ablation (FA) to induce a new follicular wave emergence. Two days after FA (Day 0), synchronized llamas were randomly allocated to three treatment groups (n = 6/group) and given 500, 750 and 1000 IU of eCG (Novormon®, Syntex, Buenos Aires, Argentina) per animal respectively to induce ovarian superstimulation. Transrectal ultrasonography were performed on Days 2, 4, and 6; and ovum pick up (OPU) was performed on Day 6. Data was evaluated by one-way analysis of variance (ANOVA), repeated measures ANOVA, and 2-tailed Chi-square. The average size (mm) of follicles was greater (p≤ 0.05) in the 1000 IU group compared to the other groups. There was a greater (p≤ 0.05) number of follicles ≥ 7 mm in the 1000 IU group compared to the 500 IU group. Number of COCs collected on Day 6 and the COC recovery rate were not different among groups. In conclusion, a single dose of 1000 IU of eCG induced the best ovarian response resulting in larger and greater number of follicles at the time of OPU.

Do women with severely diminished ovarian reserve undergoing modified natural cycles benefit from earlier trigger at smaller follicle size?

OBJECTIVE

Would trigger and oocyte collection at smaller follicle sizes decrease the risk of premature ovulation while maintaining the reproductive potential of oocytes in women with severely diminished ovarian reserve in modified natural cycle IVF?

METHODS

Retrospective cohort study including women who had at least one unsuccessful cycle (due to no response) of conventional ovarian stimulation with a high dosage of gonadotropins and subsequently underwent a modified natural cycle with a solitary growing follicle (i.e., only one follicle above >10mm at the time of trigger). The association between follicle size at trigger and various cycle outcomes was tested with regression analyses.

RESULTS

A total of 160 cycles from 110 patients were included in the analysis. Oocyte pick-up (OPU) was performed in 153 cycles, 7 cycles were canceled due to premature ovulation. Patients who received their trigger shot at smaller follicle sizes (≤15mm) had significantly lower premature ovulation and thus higher OPU rates (98.3% vs. 94.0%, adjusted OR: 8.55, 95% CI: 1.30 - 172.2, P=0.048) compared to those who received it at larger follicle sizes (>15mm). In the multivariable analyses, smaller follicle sizes at trigger (>10 to ≤13mm, >13 to ≤15mm, >15mm to ≤17mm) were not significantly associated with a lower rate of cumulus-oocyte-complex (COC), metaphase II oocytes (MIIs), or blastulation compared to the >17mm group. In sensitivity analyses including the first cycle of each couple, the maturity rate among those with a COC retrieval was highest in follicle sizes >15 to ≤17mm (92.3%) and >13 to ≤15mm (91.7%), followed by >10 to ≤13mm (85.7%) and lowest in the >17mm group (58.8%). Five euploid blastocysts developed from 48 fertilized MIIs during the study period with follicle sizes at trigger 12mm (3), 14 mm (1), and 16mm (1). Four were transferred resulting in two live births, both developing from follicles with a size at trigger of 12mm.

CONCLUSION

The ideal follicle size for triggering oocyte maturation may be smaller in women with severely diminished ovarian reserve managed on a modified natural cycle compared to conventional cut-offs. The risk of OPU cancellation was higher in women triggered above 15 mm, and the yield of mature oocytes was not adversely affected in women triggered at >13 to ≤15mm compared to >15mm to ≤17mm. Waiting for follicles to reach sizes above 17mm may be detrimental to achieving optimal outcomes. This article is protected by copyright. All rights reserved.

Effect of small follicles on clinical pregnancy and multiple pregnancy rates in intrauterine insemination: a cohort study

STUDY QUESTION

What is the effect of small follicles on clinical pregnancy and multiple pregnancy rates in women undergoing IUI with ovarian stimulation (IUI-OS)?

SUMMARY ANSWER

The presence of ≥2 small follicles with a diameter of 10-12 or 12-14 mm was associated with an increased chance of clinical pregnancy and the presence of any 12-14 mm or larger follicles, but not smaller follicles, was statistically significantly associated with an increased risk for multiple pregnancy.

WHAT IS KNOWN ALREADY

IUI-OS is widely used as the first-line treatment for unexplained or mild male factor infertility. However, IUI is associated with the risk of multiple pregnancy. While the positive association between the number of follicles ≥14 mm and the chance of pregnancy and the risk of multiple pregnancy is known, the impact of smaller follicles is uncertain.

STUDY DESIGN, SIZE, DURATION

This was a retrospective cohort study that included women undergoing IUI cycles from January 2007 to May 2021 in one assisted reproduction center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We studied the impact of the number and size of follicles on trigger day on clinical pregnancy and multiple pregnancy rates. Generalized estimation equation regression models were used to compute unadjusted and adjusted odds ratios and 95% CI in all women and only women who achieved clinical pregnancy separately. The chance of clinical pregnancy and multiple pregnancy for different numbers of small follicles in cycles with one >18-mm follicle was calculated using marginal effects estimate.

MAIN RESULTS AND THE ROLE OF CHANCE

This cohort included 12 933 IUI cycles in 7504 women. The overall clinical pregnancy rate was 16.1% (2081/12 933), with a multiple pregnancy rate of 10.5% (218/2081). In the adjusted analysis, the chance of clinical pregnancy increased significantly with the increase in the number of follicles with the diameter of 14-16, 16-18, and 18-20 mm. As for 10-12 mm [adjusted odds ratio (aOR) 1.22, 95% CI 1.02-1.46] and 12-14 mm (aOR 1.29, 95% CI 1.07-1.56) follicles, only groups with ≥2 follicles of those sizes showed significantly increased chance of clinical pregnancy. In cycles that led to pregnancy, follicles with the diameter of 12-14 mm were associated with an increased risk of multiple pregnancy (aOR 1.73, 95% CI 1.19-2.53 for one such follicle; aOR 2.27, 95% CI 1.44-3.56 for ≥2 such follicles), while 10- to 12-mm follicles were not significantly associated with multiple pregnancy (aOR 1.18, 95% CI 0.72-1.95 for ≥2 such follicles). The associations of multiple pregnancy were similar when including all cycles.

LIMITATIONS, REASONS FOR CAUTION

This was a retrospective observational study from a single center. The records of follicle diameter in our center were of a 2-mm interval which limited our ability to analyze the size of follicle as a continuous variable. Also, the number of cycles with a high number of small follicles was still limited which impeded more detailed analysis on the ≥2 follicles subgroup. Similarly, the value of some parts of the marginal probability estimation for multiple pregnancy versus pregnancy according to size and number of follicles was also limited by the low sample size of certain combinations.

WIDER IMPLICATIONS OF THE FINDINGS

Follicles larger than 10 mm, especially those ≥12 mm, may need to be clearly recorded during transvaginal ultrasound surveillance and their potential effects on both pregnancy and multiple pregnancy can be discussed with couples undergoing IUI.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Natural Science Foundation of China (Grant numbers 82201912, 82371651, and 82071615) and Shanghai Sailing Program (21YF1423200). B.W.M. is supported by an NHMRC Investigator grant (GNT1176437). B.W.M. reports consultancy for ObsEva and Merck and travel support from Merck. B.W.M. has received research funding from Ferring and Merck. The authors declare no other competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Impact of follicular size categories on oocyte quality at trigger day in young and advanced-age patients undergoing GnRH-ant therapy

Aim

To study the effect of follicle sizes of different proportions on oocyte and embryo quality in young and advanced-age patients, and provide evidence for personalized protocol adjustment.

Methods

This was a retrospective real-world data study including a total of 11,462 patients who had started their first in vitro fertilization cycle with a gonadotropin-releasing hormone antagonist (GnRH-ant) protocol during 2018-2021. We classified patients into groups according to the size of the dominant proportion of follicles on the human chorionic gonadotropin (hCG) trigger day: Large, Medium, Small, and Equal (containing equivalent proportions of all three size categories). The Cochran-Mantel-Haenszel test by different Anti-Mullerian Hormone (AMH) and antral follicle count (AFC) was used to compare factors such as the metaphase II (MII) oocyte rate, normal fertilization rate, and two pronuclei (2PN) cleavage rate between groups. General linear model (GLM) analysis was performed for inter-group comparison of the oocyte and embryo quality.

Results

In patients aged < 35 years and with AMH ≥ 1.2μg/L, the MII oocyte percentages in the Large and Medium groups were significantly higher than in the Small group (P < 0.001). The germinal vesicle (GV) oocyte and unavailable oocyte percentages in the Large and Medium groups were lower than in the Small group (P < 0.001). Among patients aged ≥ 35 years with AFC < 5 and AMH ≥ 1.2μg/L, the GV oocyte percentage in the Large group was significantly lower than in the Medium group (2.54% vs. 4.46%, P < 0.001). In patients < 35 years, the GLM demonstrated that the Large and Medium groups had positively impacted on the development of MII oocyte and live birth rate(LBR) of first embryo transfer(ET)(β>0, all P value < 0.05);and had less likely to develop into unavailable oocyte, degenerated oocyte, GV oocyte and MI oocyte rates relative to the Small group(β<0, all P value < 0.05). And among patients ≥ 35 years, the Medium group had positively impacted on the development of MII oocyte and 2PN rates relative to the Small group(β>0, all P value < 0.05); and had less likely to develop into MI oocytes relative to the Small group(β<0, all P value < 0.05). The GLM indicated that AMH, along with Gn total dose, start dose, and Gn days, had significant impact on oocyte and embryo quality. For young patients, age was not a significant influencing factor, but for advanced-age patients, age influenced the outcomes.

Conclusion

Our analysis suggests that for young patients (< 35 years), triggering when there is a high proportion of large or medium follicles results in better quality oocytes, while for older patients (≥ 35 years), it is better to trigger when the proportion of medium follicles is no less than that of small follicles. Further research is required to confirm these findings.

Optimal Timing of Ovulation Triggering to Achieve Highest Success Rates in Natural Cycles-An Analysis Based on Follicle Size and Oestradiol Concentration in Natural Cycle IVF

INTRODUCTION

Timing of ovulation triggering is essential in infertility treatments including treatments based on natural menstrual cycles. However, data on follicle size and oestradiol (E2) concentration are limited. Therefore, the model of natural cycle IVF (NC-IVF) was applied to provide more detailed information on these parameters to better schedule the optimal time for triggering ovulation.

MATERIALS AND METHODS

A retrospective cross-sectional analysis of 606 monofollicular NC-IVF cycles was performed at a university-based IVF centre from 2016 to 2019. Follicle size and E2 and LH serum concentrations were evaluated on day -5 to 0 (day 0 = day of oocyte retrieval). Ovulation was triggered if follicle size was 14-22 mm. Patients with irregular cycles, endometriosis >II°, cycles with azoospermia or cryptozoospermia and cycles with inconsistent data were excluded. All parameters were analysed inter- and intraindividually, and associations of the parameters were evaluated. Associations were adjusted for age, cause of infertility and number of previous transfers.

RESULTS

The mean age of women undergoing NC-IVF was 35.8 ± 4.0 years. Follicle size increased by 1.04 ± 0.03 mm, and E2 concentration by 167 ± 11.0 pmol/l per day.Based on a multivariate adjusted mixed model with follicle size, E2 and their interaction, the number of retrieved oocytes was associated with E2 concentration (aOR 1.91, 95% CI: 1.03-3.56; p = 0.040). Maturity of oocytes was associated not only with E2 concentration (aOR 2.01, 95% CI: 1.17-3.45; p = 0.011) but also with follicle size (aOR 1.27, 95% CI: 1.01-1.60; p = 0.039), as was the interaction of both parameters (aOR 0.96, 95% CI: 0.93-0.99; p = 0.017).LH surge was calculated to start in 25% of cases at an E2 level of 637 pmol/l, in 50% of cases at 911 pmol/l and in 75% of cases at an E2 level of 1,480 pmol/l.The live birth rate per follicle aspiration cycle was (non-significantly) higher in cycles with follicles sizes at the time of oocyte retrieval of 18-22 mm (7.7%-12.5%) versus in cycles with follicles sizes of 14-17 mm (1.6%-4.3%).

CONCLUSION

The study contributes to an optimization of infertility treatments involving natural cycles. The study gives guidance about the number of days required after follicle monitoring to schedule the optimal time for triggering ovulation.

Correlation between Pre-Ovulatory Follicle Diameter and Follicular Fluid Metabolome Profiles in Lactating Beef Cows

Induced ovulation of small pre-ovulatory follicles reduced pregnancy rates, embryo survival, day seven embryo quality, and successful embryo cleavage in beef cows undergoing fixed-time artificial insemination. RNA-sequencing of oocytes and associated cumulus cells collected from pre-ovulatory follicles 23 h after gonadotropin-releasing hormone (GnRH) administration to induce the pre-ovulatory gonadotropin surge suggested reduced capacity for glucose metabolism in cumulus cells of follicles ≤11.7 mm. We hypothesized that the follicular fluid metabolome influences metabolic capacity of the cumulus-oocyte complex and contributes to reduced embryo cleavage and quality grade observed following induced ovulation of small follicles. Therefore, we performed a study to determine the correlation between pre-ovulatory follicle diameter and follicular fluid metabolome profiles in lactating beef cows (Angus, n = 130). We synchronized the development of a pre-ovulatory follicle and collected the follicular contents approximately 20 h after GnRH administration. We then performed ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) metabolomic studies on 43 follicular fluid samples and identified 38 metabolites within pre-ovulatory follicles of increasing size. We detected 18 metabolites with a significant, positive correlation to follicle diameter. Individual and pathway enrichment analysis of significantly correlated metabolites suggest that altered glucose and amino acid metabolism likely contribute to reduced developmental competence of oocytes when small pre-ovulatory follicles undergo induced ovulation.

Relative transcript abundance in porcine cumulus cells collected from different sized follicles

Crosstalk between the oocyte and surrounding cumulus cells (CCs) is essential for the production of competent oocytes. Previous studies have analysed the relative transcript abundance in oocytes derived from small (SF: <3 mm diameter)- and medium-sized (MF: 3-6 mm diameter) follicles to determine the potential use of SF-derived oocytes in assisted reproductive technologies (ART). The aim of this study was to examine the relative transcript abundance of CCs obtained from cumulus-oocyte complexes (COCs) derived from SF and MF. Nine genes were selected according to their importance for developmental competence: AT-rich interaction domain 1B (ARID1B), bone morphogenic protein receptor 2 (BMPR2), CD44, follicle-stimulating hormone receptor (FSHR), follistatin (FST), inhibin beta-A (INHBA), luteinizing hormone receptor (LHR), nuclear receptor subfamily 2 group F member 6 (NR2F6) and vascular endothelial growth factor A (VEGFA). The expression of these genes was analysed by RT-qPCR. The results pointed to significant differences in five genes, and the relative transcript abundance of SF-derived CCs was lower in the case of INHBA, but higher in FSHR, FST, LHR and NR2F6 compared with MF-derived CCs. We provide information of gene activity in the porcine CCs from different sized follicles, thus improving our understanding of oocyte biology and providing new markers that identify viable and competent oocytes.

Follicle Size on Day of Trigger Most Likely to Yield a Mature Oocyte

OBJECTIVE

To identify follicle sizes on the day of trigger most likely to yield a mature oocyte following hCG, GnRH agonist (GnRHa), or kisspeptin during IVF treatment.

DESIGN

Retrospective analysis to determine the size of follicles on day of trigger contributing most to the number of mature oocytes retrieved using generalized linear regression and random forest models applied to data from IVF cycles (2014-2017) in which either hCG, GnRHa, or kisspeptin trigger was used.

SETTING

HCG and GnRHa data were collected at My Duc Hospital, Ho Chi Minh City, Vietnam, and kisspeptin data were collected at Hammersmith Hospital, London, UK.

PATIENTS

Four hundred and forty nine women aged 18-38 years with antral follicle counts 4-87 were triggered with hCG (n = 161), GnRHa (n = 165), or kisspeptin (n = 173).

MAIN OUTCOME MEASURE

Follicle sizes on the day of trigger most likely to yield a mature oocyte.

RESULTS

Follicles 12-19 mm on the day of trigger contributed the most to the number of oocytes and mature oocytes retrieved. Comparing the tertile of patients with the highest proportion of follicles on the day of trigger 12-19 mm, with the tertile of patients with the lowest proportion within this size range, revealed increases of 4.7 mature oocytes for hCG (P < 0.0001) and 4.9 mature oocytes for GnRHa triggering (P < 0.01). Using simulated follicle size profiles of patients with 20 follicles on the day of trigger, our model predicts that the number of oocytes retrieved would increase from a mean 9.8 (95% prediction limit 9.3-10.3) to 14.8 (95% prediction limit 13.3-16.3) oocytes due to the difference in follicle size profile alone.

CONCLUSION

Follicles 12-19 mm on the morning of trigger administration were most likely to yield a mature oocyte following hCG, GnRHa, or kisspeptin.

A retrospective analysis of ovarian stimulation with letrozole in women undergoing artificial insemination by donor

The aim of this retrospective study was to determine the clinical pregnancy rate in women undergoing letrozole ovarian stimulation and artificial insemination by donor (AID). Between 2012 and 2015, 130 natural cycles, 939 letrozole cycles and 130 letrozole plus gonadotrophin cycles were conducted. Letrozole cycles were divided into three groups according to LH concentration on the day of HCG administration (LH <10 mIU/ml and follicle size ≥18 cm; LH ≤10 to <20 mIU/ml; and LH ≥20 mIU/ml). Pregnancy rates were 17.3%, 22.4% and 26.8%, respectively (P = 0.012). In women given 10 mIU/ml LH or more, logistic regression identified oestradiol (OR 1.002, 95% CI, 1.000 to 1.004, P = 0.029) and leading follicle size (OR 0.861, 95% CI, 0.772 to 0.960, P = 0.007) as significant predictive factors of pregnancy rate; the higher the oestradiol and the smaller the follicles, the better the pregnancy rate. The pregnancy rate was significantly higher in the letrozole plus gonadotrophin group than the letrozole group (P = 0.04). Better pregnancy rates can be achieved if LH surge occurs before HCG administration, especially with higher oestradiol and lower follicle size; treatment with letrozole plus gonadotrophin was significantly more effective than letrozole alone in AID.

Signals of vitellogenesis and estrus in female hawksbill turtles

This study reports a viable means of identifying the vitellogenic cycle and limited estrus period in hawksbill turtles for the purposes of developing captive breeding program, based on the combination of blood metabolite parameters (triglyceride, total protein, and calcium levels), feeding status, and ovary condition. Follicle size of two focal captive females showed clear seasonal changes, with major development occurring between March and May (19.0-24.4 mm), and exceeding 25 mm between June and September. Triglyceride, total protein, and calcium levels dropped with follicular development and maintenance (March to October), and then began to rise when follicular retraction occurred from October onwards. The two focal turtles reduced food intake during intensive follicular development (April to May). These findings suggest that blood metabolite parameters and feeding conditions are inferred by the vitellogenic cycle. An additional 10 females exhibiting follicular development were mated with a single male for 7-day period between May and June. Follicle size was measured immediately prior to pairing, and a statistically significant difference in follicle size of 10 females was recorded between the seven failed (20.9 mm) and three successful (23.6 mm) mating events. This indicates follicle development is essential to successful mate and monitoring of vitellogenic cycle may help improve the success rates of captive hawksbill breeding programs.

A critical review of bi-dimensional and three-dimensional ultrasound techniques to monitor follicle growth: do they help improving IVF outcome?

BACKGROUND

This review focuses on the possibility of improving the outcome of human IVF by studying the follicles where oocytes grow by ultrasound techniques. A comprehensive analysis of bi-dimensional (2D) and three-dimensional (3D) ultrasound (US) assessment of the follicle size and volume is presented.

METHODS

Published reports from the year 1999 to 2014 analyzing the relationship between oocyte competence, IVF outcome and ultrasound assessment of the follicle size and volume have been critically analyzed.

RESULTS

US assessment of growing follicles has been performed mainly by 2D-US, and while overall very useful, it has been found to be of limited usefulness in predicting oocyte competence, recognize which follicles will release a mature metaphase II oocytes and decide the ideal time to trigger ovulation. In fact, a quite wide follicle size range (16-22 mm) has been reported to be associated with mature oocytes with good competence toward fertilization and embryo development. It has been also shown that smaller follicles sometimes contain mature, fertilizable oocytes. However, embryos derived from smaller follicles have probably a lower implantation potential, while follicles larger than 22 mm often contain post-mature eggs.

CONCLUSIONS

The study of follicular size by 2D-US is of limited usefulness in helping in the identification of follicles containing the best oocytes and in choosing the best moment to trigger ovulation. Possibly the value of US in this area will be improved by large prospective studies in which automated 3D-US will be used.