The effect of ovarian stimulation on aneuploidy of early aborted tissues and preimplantation blastocysts: comparison of the GnRH agonist long protocol with the GnRH antagonist protocol

Effects of ovarian stimulation on embryo euploidy: an analysis of 12 874 oocytes and 3106 blastocysts in cycles with preimplantation genetic testing for monogenic disorders

STUDY QUESTION

Does ovarian stimulation and the ovarian response affect embryo euploidy?

SUMMARY ANSWER

Ovarian stimulation and the ovarian response in women undergoing preimplantation genetic testing for monogenic disorders (PGT-M) cycles did not affect the rates of blastocyst euploidy.

WHAT IS KNOWN ALREADY

Whether or not ovarian stimulation in IVF-embryo transfer has potential effects on embryo euploidy is controversial among studies for several reasons: (i) heterogeneity of the study populations, (ii) biopsies being performed at different stages of embryo development and (iii) evolution of the platforms utilized for ploidy assessment. Patients who undergo PGT-M cycles typically have no additional risks of aneuploidy, providing an ideal study population for exploring this issue.

STUDY DESIGN SIZE DURATION

A retrospective cohort study including embryos undergoing PGT-M was conducted at a single academically affiliated fertility clinic between June 2014 and July 2021.

PARTICIPANTS/MATERIALS SETTING METHODS

A total of 617 women with 867 PGT-M cycles involving 12 874 retrieved oocytes and 3106 trophectoderm biopsies of blastocysts were included. The primary outcome of the study was median euploidy rate, which was calculated by dividing the number of euploid blastocysts by the total number of biopsied blastocysts for each cycle. Secondary outcomes included the median normal fertilization rate (two-pronuclear (2PN) embryos/metaphase II oocytes) and median blastulation rate (blastocyst numbers/2PN embryos).

MAIN RESULTS AND THE ROLE OF CHANCE

Comparable euploidy rates and fertilization rates were observed across all age groups, regardless of variations in ovarian stimulation protocols, gonadotropin dosages (both the starting and total dosages), stimulation durations, the inclusion of human menopausal gonadotrophin supplementation, or the number of oocytes retrieved (all P > 0.05). Blastulation rates declined with increasing starting doses of gonadotropins in women aged 31-34 years old (P = 0.005) but increased with increasing gonadotrophin starting doses in women aged 35-37 years old (P = 0.017). In women aged 31-34, 35-37, and 38-40 years old, blastulation rates were significantly reduced with increases in the number of oocytes retrieved (P = 0.001, <0.001, and 0.012, respectively).

LIMITATIONS REASONS FOR CAUTION

Limitations include the study's retrospective nature and the relatively small number of patients of advanced age, especially patients older than 40 years old, leading to quite low statistical power. Second, as we considered euploidy rates as outcome measures, we did not analyze the effects of ovarian stimulation on uniform aneuploidy and mosaicism, respectively. Finally, we did not consider the effects of paternal characteristics on embryo euploidy status due to the fact that blastocyst aneuploidy primarily originates from maternal meiosis. However, sperm factors might have an effect on embryo development and the blastulation rate, and therefore also the number of blastocysts analyzed. The exclusion of patients with severe teratozoospermia and the fact that only ICSI was used as the insemination technique for women undergoing PGT-M contributed to minimize the effect of paternal factors.

WIDER IMPLICATIONS OF THE FINDINGS

Ovarian stimulation and response to stimulation did not affect blastocyst euploidy rates in women undergoing PGT-M cycles. However, in women aged 31-40 years old, there was a significant decline in blastulation rates as the number of retrieved oocytes increased.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by the National Natural Science Foundation of China (Grant No. 81701407, 82301826); the National Key Research and Development Program of China (2022YFC2702901, 2022YFC2703004); China Postdoctoral Science Foundation (2022M710261), and China Postdoctoral Innovation Talent Support Program (BX20220020). There is no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

The comparision among euploidy of preimplantation blastocysts in different controlled ovary stimulation (COH) protocols

PURPOSE

To compare differences in euploidy rates for blastocysts in preimplantation genetic testing for aneuploidy (PGT-A) cycles after gonadotropin-releasing hormone agonist (GnRH-a) long and short protocols, GnRH-antagonist (GnRH-ant) protocol, progestin-primed ovarian stimulation and mild stimulation protocols, and other ovary stimulation protocols.

METHODS

This was a retrospective cohort study from the Assisted Reproductive Medicine Department of Shanghai First Maternity and Infant Hospital. A total of 1657 PGT-A cycles with intracytoplasmic sperm injection after different controlled ovary hyperstimulation protocols were analyzed, and a total of 3154 embryos were biopsied. Differences in euploidy rate per embryo biopsied, embryo euploidy rate per oocyte retrieved and cycle cancellation rate were compared.

RESULTS

For the PGT-A cycles, the euploidy rate per embryo biopsied was lower in the GnRH-ant protocol than in the GnRH-a long protocol (53.26 vs. 58.68%, respectively). Multiple linear regression showed that the GnRH-ant protocol was associated with a lower euploidy rate per embryo biopsied (β =  -0.079, p = 0.011). The euploidy rate per embryo biopsied was not affected by total gonadotropin dosage, duration of stimulation and number of oocytes retrieved. The embryo euploidy rate per oocyte retrieved was similar in all protocols and was negatively correlated with the total number of oocytes retrieved (β =  -0.003, p = 0.003).

CONCLUSION

Compared with the GnRH-a long protocol, the GnRH-ant protocol was associated with a lower euploidy rate per embryo biopsied. The total gonadotropin dosage, duration of stimulation and number of oocytes retrieved did not appear to significantly influence euploidy rates.

Correlation between controlled ovarian stimulation protocols and euploid blastocyst rate in pre-implantation genetic testing for aneuploidy cycles

BACKGROUND

Several studies have explored which COS protocol yields a higher blastocyst euploidy rate, but findings have been inconsistent. The present study aimed to explore whether controlled ovarian stimulation (COS) protocols was associated with euploid blastocyst rate in pre-implantation genetic testing for aneuploidy (PGT-A) cycles.

METHODS

The study was a retrospective study where data were obtained from three reproductive medicine centers. The study included PGT-A cycles with the GnRH-a, GnRH-ant, or PPOS protocols, and the data on patient demographics, protocols, and embryonic outcomes were collected for the PGT-A cycles performed between January 2019 and August 2022.

RESULTS

This study included 457 PGT-A cycles from three reproductive medicine centers, with 152, 126, and 179 cycles performed using the PPOS, GnRH-a, and GnRH-ant protocols, respectively. The baseline characteristics of the three groups show no significant differences were observed in female BMI, infertility type, and infertility duration among the PPOS, GnRH-a, and GnRH-ant protocol groups. The study found no significant association between Gn dosage, Gn duration, and blastocyst euploidy. The mean number of euploidy blastocysts in PPOS protocol was significantly lower than that of GnRH-a protocol and GnRH-ant protocol (0.75 ± 0.92 vs. 1.79 ± 1.78 vs. 1.80 ± 1.67). The euploidy rate per biopsy blastocyst (48.4% vs. 49.1% vs. 33.1%), per oocyte retrieved (15.0% vs. 14.7% vs. 10.5%), and per MII oocyte (17.7% vs. 16.4% vs. 11.7%) were significantly higher in the cycles using the GnRH-ant and GnRH-a protocols than that of PPOS protocol group. Regression analyses indicated that, compared with the PPOS protocol, the GnRH-ant protocol was positively associated with the euploid blastocyst rate and the mean number of euploid blastocysts, whereas the GnRH-a protocol showed no such relationship.

LIMITATIONS AND REASONS FOR CAUTION

The main limitation of this study was the retrospective design. Although this study also used other tests to account for confounding factors and reduce potential bias, multiple tests have its own weaknesses.

CONCLUSIONS

GnRH-ant protocol was the most effective for PGT-A cycles. The findings emphasize the need for personalized treatment strategies, considering patient demographics, and optimizing COS protocols to enhance the chances of successful outcomes in ART procedures.

Controlled ovarian hyperstimulation parameters are not associated with de novo chromosomal abnormality rates and clinical pregnancy outcomes in preimplantation genetic testing

OBJECTIVE

This study aimed to determine whether controlled ovarian hyperstimulation (COH) parameters influence the incidence of de novo chromosomal abnormalities (> 4 Mb) in blastocysts and, thus, clinical pregnancy outcomes in preimplantation genetic testing (PGT).

METHODS

Couples who underwent preimplantation genetic testing for structural chromosome rearrangements (PGT-SR) and monogenic disorders (PGT-M) were included in this study. The relationships of maternal age, paternal age, stimulation protocol, exogenous gonadotropin dosage, duration of stimulation, number of oocytes retrieved and estradiol (E₂) levels on human chorionic gonadotropin (hCG) trigger day with the incidence of de novo chromosomal abnormalities were assessed. Blastocysts were biopsied, and nuclear DNA was sequenced using next-generation sequencing (NGS). Clinical pregnancy outcomes after single euploid blastocyst transfers under different COH parameters were assessed.

RESULTS

A total of 1,710 and 190 blastocysts were biopsied for PGT-SR and PGT-M, respectively. The rate of de novo chromosomal abnormalities was found to increase with maternal age (p< 0.001) and paternal age (p = 0.019) in the PGT-SR group. No significant differences in the incidence of de novo chromosomal abnormalities were seen for different maternal or paternal age groups between the PGT-SR and PGT-M groups (p > 0.05). Stratification analysis by gonadotropin dosage, stimulation protocol, duration of stimulation, number of retrieved oocytes and E₂ levels on hCG trigger day revealed that de novo chromosomal abnormalities and clinical pregnancy outcomes were not correlated with COH parameters after adjusting for various confounding factors.

CONCLUSION

The rate of de novo chromosomal abnormalities was found to increase with maternal or paternal age. COH parameters were found to not influence the incidence of de novo chromosomal abnormalities or clinical pregnancy outcomes.