Is ovarian stimulation detrimental to the endometrium?

The impact of ovarian stimulation on the human endometrial microenvironment

STUDY QUESTION

How does ovarian stimulation (OS), which is used to mature multiple oocytes for ART procedures, impact the principal cellular compartments and transcriptome of the human endometrium in the periovulatory and mid-secretory phases?

SUMMARY ANSWER

During the mid-secretory window of implantation, OS alters the abundance of endometrial immune cells, whereas during the periovulatory period, OS substantially changes the endometrial transcriptome and impacts both endometrial glandular and immune cells.

WHAT IS KNOWN ALREADY

Pregnancies conceived in an OS cycle are at risk of complications reflective of abnormal placentation and placental function. OS can alter endometrial gene expression and immune cell populations. How OS impacts the glandular, stromal, immune, and vascular compartments of the endometrium, in the periovulatory period as compared to the window of implantation, is unknown.

STUDY DESIGN, SIZE, DURATION

This prospective cohort study carried out between 2020 and 2022 included 25 subjects undergoing OS and 25 subjects in natural menstrual cycles. Endometrial biopsies were performed in the proliferative, periovulatory, and mid-secretory phases.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Blood samples were processed to determine serum estradiol and progesterone levels. Both the endometrial transcriptome and the principal cellular compartments of the endometrium, including glands, stroma, immune, and vasculature, were evaluated by examining endometrial dating, differential gene expression, protein expression, cell populations, and the three-dimensional structure in endometrial tissue. Mann-Whitney U tests, unpaired t-tests or one-way ANOVA and pairwise multiple comparison tests were used to statistically evaluate differences.

MAIN RESULTS AND THE ROLE OF CHANCE

In the periovulatory period, OS induced high levels of differential gene expression, glandular-stromal dyssynchrony, and an increase in both glandular epithelial volume and the frequency of endometrial monocytes/macrophages. In the window of implantation during the mid-secretory phase, OS induced changes in endometrial immune cells, with a greater frequency of B cells and a lower frequency of CD4 effector T cells.

LARGE SCALE DATA

The data underlying this article have been uploaded to the Genome Expression Omnibus/National Center for Biotechnology Information with accession number GSE220044.

LIMITATIONS, REASONS FOR CAUTION

A limited number of subjects were included in this study, although the subjects within each group, natural cycle or OS, were homogenous in their clinical characteristics. The number of subjects utilized was sufficient to identify significant differences; however, with a larger number of subjects and additional power, we may detect additional differences. Another limitation of the study is that proliferative phase biopsies were collected in natural cycles, but not in OS cycles. Given that the OS cycle subjects did not have known endometrial factor infertility, and the comparisons involved subjects who had a similar and robust response to stimulation, the findings are generalizable to women with a normal response to OS.

WIDER IMPLICATIONS OF THE FINDINGS

OS substantially altered the periovulatory phase endometrium, with fewer transcriptomic and cell type-specific changes in the mid-secretory phase. Our findings show that after OS, the endometrial microenvironment in the window of implantation possesses many more similarities to that of a natural cycle than does the periovulatory endometrium. Further investigation of the immune compartment and the functional significance of this cellular compartment under OS conditions is warranted.

STUDY FUNDING/COMPETING INTERESTS

Research reported in this publication was supported by the National Institute of Allergy and Infectious Diseases (R01AI148695 to A.M.B. and N.C.D.), Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD109152 to R.A.), and the March of Dimes (5-FY20-209 to R.A.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or March of Dimes. All authors declare no conflict of interest.

High anti-Müllerian hormone (AMH) is associated with increased risks of ectopic pregnancy in women undergoing fresh embryo transfer cycle, a cohort study

BACKGROUND

Ectopic pregnancy is more common amongst assisted reproduction cycles and is a cause of significant maternal morbidity. Few predictive markers exist to help identify and modify risk of ectopic pregnancy in preparing for embryo transfer. The relationship between serum and AMH and ectopic pregnancy rate is unknown.

METHODS

This was a retrospective cohort study investigating women who underwent fresh embryo transfer cycles from January 2017 to December 2019 in Peking University Third Hospital. The primary outcome was ectopic pregnancy. Restricted cubic splines with four knots for AMH concentration (0-3, 3-6, 6-12, 12-max) were used to map out the non-linear relationship between the predicted ectopic pregnancy rate and the serum AMH concentration. Log binomial regression was used to test the crude risk ratio (cRR) and the adjusted risk ratio (aRR) after adjustment for confounders with 95% confidence intervals (CI) to determine the difference across various groups.

RESULTS

A total of 13,718 cycles in women undergoing fresh embryo transfer were eligible for analysis. The ectopic pregnancy rate was 1.3% per embryo transfer cycle initiated and 3.3% per pregnancy. Serum AMH concentrations were higher amongst women with ectopic pregnancy than in women with a confirmed intrauterine pregnancy or heterotopic pregnancy or who did not become pregnant (Mean levels: 4.0 ng/ml vs 3.2 ng/ml, 1.7 ng/ml, and 2.8 ng/ml). An AMH concentration of 7 ng/ml represented the best cut-off value to predict ectopic pregnancy. The ectopic pregnancy rate was 3.4% per cycle and 7.5% per pregnancy in women with AMH levels ≥ 7 ng/ml; and 1.2% per cycle and 2.9% per pregnancy in women with AMH levels < 7 ng/ml. Serum AMH concentration ≥ 7 ng/ml was associated with an increased risk of ectopic pregnancy in all fresh embryo transfer cycles started (aRR = 2.35 (1.45, 3.58)) as well in women who became pregnant (aRR = 2.23 (1.49, 3.33).

CONCLUSIONS

Baseline AMH concentration ≥ 7 ng/ml is associated with an increased risk of ectopic pregnancy in fresh embryo transfer cycles.

High birth weight and greater gestational age at birth in singletons born after frozen compared to fresh embryo transfer

OBJECTIVE

While many studies agree that the fetal birth weight is higher after frozen embryo transfer (FET), few studies have explored the difference in fetal weight change during such pregnancies. This cohort study was to identify the difference in fetal birth weight and gestational age at birth between singletons born following fresh ET and those born following FET.

MATERIALS AND METHODS

This was a hospital-based cohort study using clinical data from the Kaohsiung Chang Gung Memorial Hospital Obstetric and Neonatal Database from January 1, 2007, to December 1, 2018. A sample of 784 eligible women who had singleton pregnancies and live-born deliveries after 428 fresh ET or 356 FET between January 2007 and December 2018.

RESULTS

Compared with those in the fresh ET group, singletons in the FET group had higher birth weight (3137 g [2880-3441 g] vs. 3060 g [2710-3340 g], p < 0.05), were born later (39.0 weeks of gestation [38.0-40.0 weeks] vs. 38.0 weeks of gestation [37.0-39.0 weeks], p < 0.05), and had a lower incidence of preterm birth (10.4% vs. 15.2%, p < 0.05). The difference in birth weight was not associated with maternal body weight (BW) or body mass index, increase in maternal BW in the third trimester, but related to the total increase in maternal BW during pregnancy.

CONCLUSIONS

The birthweight of singletons born following FET and fresh ET became significant in the late third trimester. The main reason is that singletons conceived from FET were at a lower relative risk of preterm delivery and had a higher gestational age at birth.

The Combined Use of Medium- and Short-Chain Fatty Acids Improves the Pregnancy Outcomes of Sows by Enhancing Ovarian Steroidogenesis and Endometrial Receptivity

Fatty acids play important roles in maintaining ovarian steroidogenesis and endometrial receptivity. Porcine primary ovarian granulosa cells (PGCs) and endometrial epithelial cells (PEECs) were treated with or without medium- and short-chain fatty acids (MSFAs) for 24 h. The mRNA abundance of genes was detected by fluorescence quantitative PCR. The hormone levels in the PGCs supernatant and the rate of adhesion of porcine trophoblast cells (pTrs) to PEECs were measured. Sows were fed diets with or without MSFAs supplementation during early gestation. The fecal and vaginal microbiomes were identified using 16S sequencing. Reproductive performance was recorded at parturition. MSFAs increased the mRNA abundance of genes involved in steroidogenesis, luteinization in PGCs and endometrial receptivity in PEECs (p < 0.05). The estrogen level in the PGC supernatant and the rate of adhesion increased (p < 0.05). Dietary supplementation with MSFAs increased serum estrogen levels and the total number of live piglets per litter (p < 0.01). Moreover, MSFAs reduced the fecal Trueperella abundance and vaginal Escherichia-Shigella and Clostridium_sensu_stricto_1 abundance. These data revealed that MSFAs improved pregnancy outcomes in sows by enhancing ovarian steroidogenesis and endometrial receptivity while limiting the abundance of several intestinal and vaginal pathogens at early stages of pregnancy.

Differences in Ectopic Pregnancy Rates between Fresh and Frozen Embryo Transfer after In Vitro Fertilization: A Large Retrospective Study

Ectopic pregnancy (EP) is increasingly found in women treated with in vitro fertilization and embryo transfer (IVF−ET). With the development of the freeze-all policy in reproductive medicine, it is controversial whether frozen embryo transfer (FET) could reduce the rate of EP. In this single-center, large-sample retrospective study, we analyzed 16,048 human chorionic gonadotrophin (hCG)-positive patients who underwent fresh embryo transfer (ET) or FET cycles between January 2013 and March 2022. Throughout the study, the total EP rate was 2.09% (336/16,048), 2.16% (82/3803) in the ET group, and 2.07% (254/12,245) in the FET group. After adjustment for age, infertility causes, and other confounding factors, logistic regression results showed no statistical difference in EP rates between FET and ET groups (odds ratio (OR) 0.93 (0.71−1.22), p > 0.05). However, among the 3808 patients who underwent fresh ET cycles, the OR for EP was significantly lower in the long agonist protocol group than in the gonadotropin-releasing hormone antagonist (GnRH-ant) protocol group (OR 0.45 (0.22−0.93), p < 0.05). Through a large retrospective study, we demonstrated a slightly lower EP rate in FET cycles than in fresh ET cycles, but there was no significant difference. The long agonist protocol in ET cycles had a significantly lower risk of EP than the GnRH-ant protocol.

Evaluating the benefit of measuring serum progesterone prior to the administration of HCG: effect of the duration of late-follicular elevated progesterone following ovarian stimulation on fresh embryo transfer live birth rates

RESEARCH QUESTION

Progesterone overproduction during ovarian stimulation is associated with lower live birth rates (LBR) after fresh embryo transfer. Therefore, circulating P concentrations on the day of HCG administration are frequently measured in clinical practice and followed by an elective cryopreservation strategy whenever late-follicular elevated P (LFEP) occurs. A recent study concluded that the duration of LFEP >1.00 ng/mL prior to HCG administration may also affect clinical pregnancy rates. The objective of this current study was to assess whether this hypothesis was reproducible using LBR as the primary outcome.

DESIGN

Retrospective analysis including women undergoing IVF/ICSI between 2010-2015. LBR were compared among different P elevation duration subgroups (0, 1 or >1 day) using two LFEP thresholds (>1.00 ng/mL and >1.50 ng/mL).

RESULTS

The duration of LFEP >1.00 ng/mL was not associated with a significant decrease in LBR according to whether the patient had LFEP lasting for 0, 1 or >1 days (29.9%, 30.3% and 26.3%, respectively). Conversely, when using >1.50 ng/mL as the LFEP threshold, LBR decreased significantly (30.3% 20.4% and 20.5%, respectively). However, the relative frequency of having LFEP >1.50 ng/mL for >1 day was exceedingly rare (1.9%) and the additional benefit of evaluating LFEP beyond the day of HCG triggering no longer remained statistically significant after confounder-adjustment with multivariable regression analysis.

CONCLUSION

These results suggest a lack of benefit in measuring serum P in the days preceding HCG administration, since LBR in women with LFEP >1 day do not vary significantly from those with LFEP detected only on the day of HCG administration.

Potential Marker Pathways in the Endometrium That May Cause Recurrent Implantation Failure

The aim of this prospective cohort study was to identify altered biologic processes in the endometrium that may be potential markers of receptive endometrium in patients with repeated implantation failure (RIF) as compared with fertile controls. The study was conducted in a university-affiliated in vitro fertilization (IVF) gynecology clinic and molecular biology and genetics laboratory. Healthy fertile controls (n = 24) and patients with RIF (n = 24) were recruited. Window of implantation gene profiling associated with RIF was performed. Six hundred forty-one differentially expressed genes were identified, and 44 pathways were found enriched. Upon clustering of the enriched pathways, 9 representative pathways were established. The important pathways that were identified included circadian rhythm, pathways in cancer, proteasome, complement and coagulation cascades, citrate cycle, adherens junction, immune system and inflammation, cell cycle, and renin-angiotensin system. The involvement of the circadian rhythm pathway and other related pathways may alter the endometrium's functioning to ultimately cause RIF. Furthermore, we found that the pathogenesis of RIF was multifaceted and that numerous processes were involved. We believe that a better understanding of the underlying mechanisms of RIF will ultimately give rise to better treatment opportunities and to better outcomes in IVF.

Prominin-2 Prevents the Formation of Caveolae in Normal and Ovarian Hyperstimulated Pregnancy

During early pregnancy, uterine epithelial cells (UECs) become less adherent to the underlying basal lamina and are subsequently removed so the blastocyst can invade the underlying stroma. This process involves the removal of focal adhesions from the basal plasma membrane of UECs. These focal adhesions are thought to be internalized by caveolae, which significantly increase in abundance at the time of blastocyst implantation. A recent in vitro study indicated that prominin-2 prevents the formation of caveolae by sequestering membrane cholesterol. The present study examines whether prominin-2 affects the formation of caveolae and loss of focal adhesions in UECs during normal and ovarian hyperstimulation (OH) pregnancy in the rat. At the time of fertilization during normal pregnancy, prominin-2 is distributed throughout the basolateral plasma membrane. However, at the time of implantation and coincident with an increase in caveolae, prominin-2 is lost from the basal plasma membrane. In contrast, prominin-2 remains in the basolateral plasma membrane throughout OH pregnancy. Transmission electron microscopy showed that this membrane contained few caveolae throughout OH pregnancy. Our results indicate that prominin-2 prevents the formation of caveolae. We suggest the retention of prominin-2 in the basal plasma membrane during OH pregnancy prevents the formation of caveolae and is responsible for the retention of focal adhesions in this membrane, thereby contributing to the reduced implantation rate observed after such treatments.

Evaluation of Progesterone and Ovulation-stimulating Drugs on the Glandular Epithelium and Angiogenesis in Mice

Background:

Human endometrium is a dynamic tissue during the menstrual cycle can be influenced by ovarian hormones. The purpose of this study was to evaluate the endometrium angiogenesis under the influence of human menopausal gonadotropin and human chorionic gonadotropin (HMG and HCG) that stimulate ovulation and progesterone.

Materials and Methods:

In this study, thirty adult female mice were randomly divided into three groups as: control, gonadotropin and gonadotropin + progesterone. The mice in the other two groups except the control group received 7.5 IU HMG and later HCG. Subsequently, the mice were placed in a cage for mating. Gonadotropin + progesterone group was administered, 1 mg/mouse progesterone in 24, 48, and 72 h interval, after HMG injection. Ninety-six hours after HMG injection, animals were sacrificed, and their uterine specimens were prepared by immunohistochemistry technique for light microscopic studies, and statistical analysis was carried out.

Results:

Endometrium angiogenesis in control group showed that mean ± standard deviation was 24.15 ± 11.15, gonadotropin group was 62.50 ± 24.16, and gonadotropin + progesterone group was 41.85 ± 19.54. Significant difference between the control group and gonadotropin group and between the control group and gonadotropin + progesterone was observed. Statistically significant differences were observed in all groups in the endometrial angiogenesis (P < 0.05).

Conclusion:

Ovarian induction with gonadotropins and gonadotropins + progesterone could not change the morphometrically index of endometrial glandular epithelium in mice. Ovarian stimulation followed by progesterone injection could modify the angiogenesis of mice endometrium.

Outcome Analysis of Day-3 Frozen Embryo Transfer v/s Fresh Embryo Transfer in Infertility: A Prospective Therapeutic Study in Indian Scenario

INTRODUCTION

Advanced fertilization techniques like frozen embryo transfer (FET) and assisted reproductive technology have become popular and commonly used methods to treat patients suffering from infertility. Incidences of infertility are on a rise due to increased representation of females in the work place, delay in marriages, stress, and ignorance.

METHODS

We performed this prospective therapeutic study to compare FET and fresh embryo transfer in the treatment of infertility in terms of conception rate, patient acceptance, complications, and patient's compliance. A prospective screening therapeutic study on 108 patients, from September 2013 to September 2014 in Karnataka, India, randomized the patients into 2 groups (n = 54), Group-I treated with day-3 FET while Group-II was treated with fresh embryo transfer, after performing ICSI.

RESULTS

In 108 patients, 45 % patients were within 35 years of age, 35 % were in the age group 35-39. Significantly, 22 (40.75 %) patients treated with FET conceived (P = 0.022), whereas 16 (29.63 %) patients treated with fresh embryo transfer conceived (P = 0.59).

DISCUSSION

There is limited published literature from the subcontinent, comparing techniques like FET and embryo transfers in the treatment of infertility. Awareness and economic reforms must be formulated in India to facilitate individuals facing infertility problems to conceive.

CONCLUSION

FET has better and significant conception rates compared to fresh embryo transfers. FET shares an advantage of providing good quality embryos for future and subsequent implantations in cases of failure. Patient counseling and motivation play a pivotal role in the success of therapeutic procedure.

Changes in receptivity epithelial cell markers of endometrium after ovarian stimulation treatments: its role during implantation window

Background

To compare the expression of receptivity markers in epithelial and stromal cells in the endometrium of ovulatory women and infertile with hypothalamic pituitary dysfunction (HPD), untreated or treated with clomiphene citrate (CC), or with recombinant follicle stimulating hormone (rFSH).

Methods

Twelve control ovulatory and 32 anovulatory women, 22 of whom received ovulation induction with CC (n = 12) or rFSH (n = 10). Endometrial biopsies were obtained during the mid-secretory phase. Hormonal secretion was measured by chemiluminescence immunoassay, endometrial dating and cellular expression and distribution of receptivity proteins were evaluated by quantitative immunohistochemistry.

Results

CC or rFSH treatments, modified the expression of epithelial receptivity markers, such as Glycodelin A, beta-catenin, CD166/ALCAM and IGF-1R, but not in stromal markers. Also, a change in their cell distribution was observed.

Conclusions

Treatment of infertile women with HPD modified the expression and distribution of receptivity markers in the mid-secretory phase of the endometrium in epithelial but not stromal cells, which can help to explain changes in the receptivity of the endometrium during treatments and suggest an important role of these cells in the receptivity window.

Electronic supplementary material

The online version of this article (doi:10.1186/s12978-015-0034-7) contains supplementary material, which is available to authorized users.

Should mild stimulation be the order of the day?

Mild stimulation protocols aim to reduce the physical, financial and emotional burden associated with the conventional IVF protocol without compromising the pregnancy rate. Such protocols help to decrease the complications and the discomfort related to the prolonged administration of agonist and large doses of gonadotrophins, by limiting the number of oocytes recruited to no more than eight. The per cycle pregnancy rates are lower though the cumulative pregnancy rate in a year is equivalent. This CPR comes by going through earlier repeat cycles. Whether this reduces the physical, emotional or financial burden remains a matter of debate. There is need to standardize these protocol and do more trials to compare the two effectively. Till such time there is a clear benefit above the conventional protocol it will not be the protocol of choice with most physicians.

Guidelines for the design, analysis and interpretation of 'omics' data: focus on human endometrium

BACKGROUND

'Omics' high-throughput analyses, including genomics, epigenomics, transcriptomics, proteomics and metabolomics, are widely applied in human endometrial studies. Analysis of endometrial transcriptome patterns in physiological and pathophysiological conditions has been to date the most commonly applied 'omics' technique in human endometrium. As the technologies improve, proteomics holds the next big promise for this field. The 'omics' technologies have undoubtedly advanced our knowledge of human endometrium in relation to fertility and different diseases. Nevertheless, the challenges arising from the vast amount of data generated and the broad variation of 'omics' profiling according to different environments and stimuli make it difficult to assess the validity, reproducibility and interpretation of such 'omics' data. With the expansion of 'omics' analyses in the study of the endometrium, there is a growing need to develop guidelines for the design of studies, and the analysis and interpretation of 'omics' data.

METHODS

Systematic review of the literature in PubMed, and references from relevant articles were investigated up to March 2013.

RESULTS

The current review aims to provide guidelines for future 'omics' studies on human endometrium, together with a summary of the status and trends, promise and shortcomings in the high-throughput technologies. In addition, the approaches presented here can be adapted to other areas of high-throughput 'omics' studies.

CONCLUSION

A highly rigorous approach to future studies, based on the guidelines provided here, is a prerequisite for obtaining data on biological systems which can be shared among researchers worldwide and will ultimately be of clinical benefit.

Effects of "Bu Shen Huo Xue Decoction" on the Endometrial Morphology and Expression of Leukaemia Inhibitory Factor in the Rat Uterus during the Oestrous Cycle

The purpose of this study was to explore the positive effects of Bu Shen Huo Xue Decoction (BSHXF) on assisted reproduction. The study aimed to evaluate whether BSHXD could improve endometrial morphology and increase the expression of LIF in a gonadotrophin-releasing hormone agonists (GnRHa) long protocol-induced rat model during metestrus, diestrus, proestrus, and oestrus. The BSHXD group presented significantly increased endometrium thickness and decreased MVD compared with the GnRHa long protocol group. In addition, the expression of LIF was significantly higher in the BSHXD group. There were no significant differences between the control group and the BSHXD group in terms of MVD and LIF expression. These results suggested that BSHXD can improve the endometrium development, reduce the abnormal angiogenesis, and increase the expression of receptivity markers in a GnRHa long protocol-induced rat model during the oestrous cycle, which might result in an endometrial environment better suited for female reproduction.

A new ovarian response prediction index (ORPI): implications for individualised controlled ovarian stimulation

BACKGROUND

The objective was to present a new ovarian response prediction index (ORPI), which was based on anti-Müllerian hormone (AMH) levels, antral follicle count (AFC) and age, and to verify whether it could be a reliable predictor of the ovarian stimulation response.

METHODS

A total of 101 patients enrolled in the ICSI programme were included. The ORPI values were calculated by multiplying the AMH level (ng/ml) by the number of antral follicles (2-9 mm), and the result was divided by the age (years) of the patient (ORPI=(AMH x AFC)/Patient age).

RESULTS

The regression analysis demonstrated significant (P<0.0001) positive correlations between the ORPI and the total number of oocytes and of MII oocytes collected. The logistic regression revealed that the ORPI values were significantly associated with the likelihood of pregnancy (odds ratio (OR): 1.86; P=0.006) and collecting greater than or equal to 4 oocytes (OR: 49.25; P<0.0001), greater than or equal to 4 MII oocytes (OR: 6.26; P<0.0001) and greater than or equal to 15 oocytes (OR: 6.10; P<0.0001). Regarding the probability of collecting greater than or equal to 4 oocytes according to the ORPI value, the ROC curve showed an area under the curve (AUC) of 0.91 and an efficacy of 88% at a cut-off of 0.2. In relation to the probability of collecting greater than or equal to 4 MII oocytes according to the ORPI value, the ROC curve had an AUC of 0.84 and an efficacy of 81% at a cut-off of 0.3. The ROC curve for the probability of collecting greater than or equal to 15 oocytes resulted in an AUC of 0.89 and an efficacy of 82% at a cut-off of 0.9. Finally, regarding the probability of pregnancy occurrence according to the ORPI value, the ROC curve showed an AUC of 0.74 and an efficacy of 62% at a cut-off of 0.3.

CONCLUSIONS

The ORPI exhibited an excellent ability to predict a low ovarian response and a good ability to predict a collection of greater than or equal to 4 MII oocytes, an excessive ovarian response and the occurrence of pregnancy in infertile women. The ORPI might be used to improve the cost-benefit ratio of ovarian stimulation regimens by guiding the selection of medications and by modulating the doses and regimens according to the actual needs of the patients.

Fresh embryo transfer versus frozen embryo transfer in in vitro fertilization cycles: a systematic review and meta-analysis

OBJECTIVE

To examine the available evidence to assess if cryopreservation of all embryos and subsequent frozen embryo transfer (FET) results in better outcomes compared with fresh transfer.

DESIGN

Systematic review and meta-analysis.

SETTING

Centers for reproductive care.

PATIENT(S)

Infertility patient(s).

INTERVENTION(S)

An exhaustive electronic literature search in MEDLINE, EMBASE, and the Cochrane Library was performed through December 2011. We included randomized clinical trials comparing outcomes of IVF cycles between fresh and frozen embryo transfers.

MAIN OUTCOME MEASURE(S)

The outcomes of interest were ongoing pregnancy rate, clinical pregnancy rate, and miscarriage.

RESULT(S)

We included three trials accounting for 633 cycles in women aged 27-33 years. Data analysis showed that FET resulted in significantly higher ongoing pregnancy rates and clinical pregnancy rates.

CONCLUSION(S)

Our results suggest that there is evidence that IVF outcomes may be improved by performing FET compared with fresh embryo transfer. This could be explained by a better embryo-endometrium synchrony achieved with endometrium preparation cycles.

Endometrial expression of selected genes in patients achieving pregnancy spontaneously or after ICSI and patients failing at least two ICSI cycles

The objective of this study was to identify the endometrial gene expression profile in receptive phase, which could represent a useful prognostic tool for selecting IVF patients. Endometrial expression of 47 selected genes biopsied during the window of implantation in natural cycles was compared between patients who achieved a successful pregnancy spontaneously or after subsequent intracytoplasmic sperm injection (ICSI) cycles and patients who did not achieve a pregnancy after at least two failed ICSI cycles. The comparative analysis showed significantly different levels of expression in 19 genes, five implicated in apoptosis (CASP8, FADD, CASP10, APAF1, ANXA4), three in immunity (LIF, SPP1, C4BPA), five in transcriptional activity (MSX1, HOXA10, MSX2, HOXA11, GATA2), two in lipid metabolism (LEPR, APOD) and four in oxidative metabolism (AOX1, ALDH1A3, GPX3, NNMT). The evidence for these genes being differently expressed could represent the starting point of identifying the ideal receptive endometrial gene expression profile, which could be used in the future as a prognostic tool for IVF patients. Gene expression analysis technology has opened new important perspectives on the study of the physiological processes of different tissues and organs. Specifically for the endometrium, it would be really interesting to find out an endometrial gene expression profile of receptive phase, which could be used in future as a useful prognostic tool for selecting IVF patients. To achieve this aim, the objective of the present paper was the comparison of endometrial expression in natural cycles of 47 selected genes between the biopsies of patients who achieved a successful pregnancy, either spontaneously or after subsequent ICSI cycles, and those of patients who did not achieve a pregnancy after at least two failed ICSI cycles. The comparative analysis showed a significant different expression in 19 genes: five implicated in programmed cell death, known as apoptosis (CASP8, FADD, CASP10, APAF1, ANXA4), three in immunity (LIF, SPP1, C4BPA), five in transcriptional activity (MSX1, HOXA10, MSX2, HOXA11, GATA2), two in lipid metabolism (LEPR, APOD) and four in oxidative metabolism (AOX1, ALDH1A3, GPX3, NNMT). The evidence of these genes being differently expressed could represent the starting point of identifying the ideal receptive endometrial gene expression profile which could be used in the future as a prognostic tool for IVF patients.

The genomics of the human endometrium

The endometrium is a complex tissue that lines the inside of the endometrial cavity. The gene expression of the different endometrial cell types is regulated by ovarian steroids and paracrine-secreted molecules from neighbouring cells. Due to this regulation, the endometrium goes through cyclic modifications which can be divided simply into the proliferative phase, the secretory phase and the menstrual phase. Successful embryo implantation depends on three factors: embryo quality, the endometrium's state of receptivity, and a synchronised dialogue between the maternal tissue and the blastocyst. There is a need to characterise the endometrium's state of receptivity in order to prevent reproductive failure. No single molecular or histological marker for this status has yet been found. Here, we review the global transcriptomic analyses performed in the last decade on a normal human endometrium. These studies provide us with a clue about what global gene expression can be expected for a non-pathological endometrium. These studies have shown endometrial phase-specific transcriptomic profiles and common temporal gene expression patterns. We summarise the biological processes and genes regulated in the different phases of natural cycles and present other works on different conditions as well as a receptivity diagnostic tool based on a specific gene set profile. This article is part of a Special Issue entitled: Molecular Genetics of Human Reproductive Failure.

GnRH agonist versus GnRH antagonist in assisted reproduction cycles: oocyte morphology

BACKGROUND

The selection of developmentally competent human gametes may increase the efficiency of assisted reproduction. Spermatozoa and oocytes are usually assessed according to morphological criteria. Oocyte morphology can be affected by the age, genetic characteristics, and factors related to controlled ovarian stimulation. However, there is a lack of evidence in the literature concerning the effect of gonadotropin-releasing hormone (GnRH) analogues, either agonists or antagonists, on oocyte morphology. The aim of this randomized study was to investigate whether the prevalence of oocyte dysmorphism is influenced by the type of pituitary suppression used in ovarian stimulation.

METHODS

A total of 64 patients in the first intracytoplasmic sperm injection (ICSI) cycle were prospectively randomized to receive treatment with either a GnRH agonist with a long-term protocol (n: 32) or a GnRH antagonist with a multi-dose protocol (n: 32). Before being subjected to ICSI, the oocytes at metaphase II from both groups were morphologically analyzed under an inverted light microscope at 400x magnification. The oocytes were classified as follows: normal or with cytoplasmic dysmorphism, extracytoplasmic dysmorphism, or both. The number of dysmorphic oocytes per total number of oocytes was analyzed.

RESULTS

Out of a total of 681 oocytes, 189 (27.8%) were morphologically normal, 220 (32.3%) showed cytoplasmic dysmorphism, 124 (18.2%) showed extracytoplasmic alterations, and 148 (21.7%) exhibited both types of dysmorphism. No significant difference in oocyte dysmorphism was observed between the agonist- and antagonist-treated groups (P>0.05). Analysis for each dysmorphism revealed that the most common conditions were alterations in polar body shape (31.3%) and the presence of diffuse cytoplasmic granulations (22.8%), refractile bodies (18.5%) and central cytoplasmic granulations (13.6%). There was no significant difference among individual oocyte dysmorphisms in the agonist- and antagonist-treated groups (P>0.05).

CONCLUSIONS

Our randomized data indicate that in terms of the quality of oocyte morphology, there is no difference between the antagonist multi-dose protocol and the long-term agonist protocol. If a GnRH analogue used for pituitary suppression in IVF cycles influences the prevalence of oocyte dysmorphisms, there does not appear to be a difference between the use of an agonist as opposed to an antagonist.

Detrimental effects of high-dose gonadotropin on outcome of IVF: making a case for gentle ovarian stimulation strategies

OBJECTIVE

Limited data identify detrimental influences of aggressive use of gonadotropins (G) for controlled ovarian hyperstimulation (COH); the underlying mechanisms however remain unclear. We report on the relationship between G dose and in vitro fertilization (IVF) cycle parameters (ovarian response, endometrial thickness [EMT]) and cycle outcome (implantation rate [IR] and clinical pregnancy [CP] rate) in a cohort of women undergoing IVF.

METHODS

Retrospective analysis of fresh embryo transfer (ET) cycles. Univariate and multivariable regression analyses assessed relationship between G dose and outcomes of interest.

RESULTS

Higher G dose related positively with advancing age (P < .001) and inversely with EMT (P < .001). The overall CP rate was 30%. Significantly lower IR (.003) and CP rate (.002) were observed across increasing tertiles of G dose. Increasing G dose was identified as an independent negative predictor of EMT after adjusting for age, COH protocol and duration, infertility diagnosis, and ovarian response (P = .016). Adjusting for age, suppression protocol (gonadotropin-releasing hormone agonist vs antagonist), infertility diagnoses, EMT, quality, and cleavage of ET, lower G dose was an independent positive predictor of CP rate (odds ratio for CP rate was 1.57 for G dose in middle compared to the highest G dose quartile (95% confidence interval 1.09-2.24). Stratified analyses identified detrimental associations of higher G dose with CP rate to be relevant in women aged 35 years and younger.

CONCLUSIONS

Our analyses suggest detrimental influences of higher G dose on the endometrium and confirm the previously reported adverse association between higher G dose and IVF outcome. Gentler COH regimens may be of particular benefit in women aged ≤35 years.

Stillbirth and neonatal mortality in monochorionic and dichorionic twins: a population-based study

BACKGROUND

Chorionicity is one of the main predictors of higher perinatal mortality in twins. The aim of this large population-based study was to analyse stillbirth and neonatal mortality by cause of death and chorionicity and to quantify the risk of stillbirth by gestational age in dichorionic (DC) and monochorionic (MC) twins.

METHODS

We used data on twin maternities delivered in the North of England from 1998 to 2007 and notified to the Northern Survey of Twin and Multiple Pregnancy. Prospective risk of stillbirth by gestational age at death was calculated using number of stillborn fetuses at or beyond a given gestational period per 1000 fetuses in ongoing pregnancies.

RESULTS

There were 4565 twin maternities (9130 twins) with an overall twinning rate of 14.9 per 1000 maternities. The overall stillbirth and neonatal mortality rates in twins during 1998-2007 were 18.0/1000 births and 23.0/1000 live births, respectively. Stillbirth and neonatal mortality rates were significantly higher in MC than DC twins: 44.4 versus 12.2 per 1000 births [relative risk (RR): 3.6; 95% CI: 2.6-5.1], and 32.4 versus 21.4 per 1000 live births (RR: 1.5; 95% CI: 1.04-2.2), respectively. There was no significant improvement over time in either stillbirth or neonatal mortality rates in either group. The prospective risk of antepartum stillbirth was higher for MC than DC twins at all preterm gestations and the highest risk was before 28 weeks' gestation.

CONCLUSIONS

MC twins have higher rates of stillbirth and neonatal mortality than DC twins, and rates did not improve over 1998-2007. The prospective risk of antepartum stillbirth is much higher for MC twins at all gestational ages.

Different ART outcomes at increasing peak estradiol levels with long and antagonist protocols: retrospective insights from ten years experience

PURPOSE

To evaluate the impact of high estradiol (E2) levels on assisted reproductive technologies outcomes in high responders (≥12 oocytes retrieved) according to the controlled ovarian stimulation protocol (COS) used.

METHODS

Clinical retrospective evaluation of total, clinical pregnancy and implantation rates in ART cycles performed in high responders according to the COS protocol used (long or antagonist) at Pathophysiology Unit of Human Reproduction and Sperm Bank of Pordenone from June 2000 to December 2010.

RESULTS

In high responders total, clinical and implantation rates were significantly higher in long if compared with antagonist protocol with peak estradiol level ≤3,000 pg/ml; on the contrary there was a significantly higher implantation rate with antagonist than long protocol with peak estradiol >3,000 pg/ml. However in this subgroup of patients total and clinical pregnancy rates showed only a trend favouring antagonist possibly due to a statistical β error.

CONCLUSIONS

In high responders long protocol seems to work better than antagonist when peak E2 is lower than 3,000 pg/ml but the opposite may be true for cycles with higher E2 levels.

Endometrial gene expression in the window of implantation is altered in obese women especially in association with polycystic ovary syndrome

OBJECTIVE

To determine whether luteal phase endometrial transcriptome is altered in obese women during the window of implantation (WOI), considering the presence of infertility, fat distribution and association with polycystic ovary syndrome (PCOS).

DESIGN

Prospective study.

SETTING

University-affiliated infertility clinic, between May 2007 and March 2009.

PATIENT(S)

One control group of women with normal weight (n=4), and four study groups of obese women (n=6 each one) according to the association with infertility, PCOS, and ovarian stimulation.

INTERVENTION(S)

The endometrium was biopsied 7 days after LH surge or hCG administration in 28 women.

MAIN OUTCOME MEASURE(S)

Endometrial gene expression during the WOI.

RESULT(S)

One hundred and fifty-one genes were dysregulated in obese groups compared with controls. This dysregulation was more pronounced when infertility was associated. The biologic processes of these genes belonged mainly to development and regulation of different biological functions such as transcription and biosynthesis. The molecular functions overrepresented were transcription and peptide receptor activity. The endometrium of obese women with PCOS showed dysregulated genes related to biologic processes such as development, morphogenesis, and the immune system, as well as different molecular functions such as protein binding, binding, growth factor activity, and carboxylic acid transmembrane transporter activity. Some of these genes have been previously related to implantation and unexplained infertility.

CONCLUSION(S)

Obese women present a different endometrial gene expression than controls during the WOI, which is more pronounced when infertility or polycystic ovary syndrome are associated.

Milder is better? Advantages and disadvantages of "mild" ovarian stimulation for human in vitro fertilization

In the last decades, several steps have been made aiming at rendering human IVF more successful on one side, more tolerable on the other side. The "mild" ovarian stimulation approach, in which a lower-than-average dose of exogenous gonadotropins is given and gonadotropin treatment is started from day 2 to 7 of the cycle, represents a significant step toward a more patient's friendly IVF. However, a clear view of its virtues and defects is still lacking, because only a few prospective randomized trials comparing "mild" vs. conventional stimulation exist, and they do not consider some important aspects, such as, e.g., thawing cycles. This review gives a complete panorama of the "mild" stimulation philosophy, showing its advantages vs. conventional ovarian stimulation, but also discussing its disadvantages. Both patients with a normal ovarian responsiveness to exogenous gonadotropins and women with a poor ovarian reserve are considered. Overall, we conclude that the level of evidence supporting the use of "mild" stimulation protocols is still rather poor, and further, properly powered prospective studies about "mild" treatment regimens are required.

Genomics analysis: endometrium

Microarray technology has been used widely in gynecology. Numerous studies have used this method to address biological questions related to human endometrium. The cyclic changes of endometrium confer special characteristics that should be considered before genomic analysis. The present study reviews these considerations and the principles of transcriptomic analysis through an example of a comparison of three different phases of the menstrual cycle.

Characterization of endometrial growth in proliferative and early luteal phase in IVF cycles

Human endometrium has a definite role in implantation, although knowledge about its modifications in the course of IVF cycles is still limited. This study was performed to characterize endometrial growth throughout stimulation treatment in women undergoing IVF cycles, regardless of clinical outcomes. Endometrial growth was longitudinally evaluated by ultrasonography in the first induced ovarian stimulation cycle (717 patients). Acceleration and length of significant growth were used to assess the slope of the growth curve mathematically. Endometrial growth showed a parabolic trend and final thickness was significantly affected by age (P < 0.01). Endometria that tended to overgrowth had a more rapid and longer growth during the whole phase. A similar stimulation treatment was repeated within 6 months of the first one and a second evaluation was carried out to verify whether similar growth occurred. Similar growth was observed in 76% of the patients, with an absolute difference between the two cycles of <4 mm in 84% of cases. The endometrium seems to have an individual intrinsic potential that can be expressed regardless of the stimulation protocol. This supports the hypothesis that individual factors (intrinsic properties of the endometrium) significantly affect endometrial growth.

Mild IVF using GnRH agonist long protocol is possible: comparing stimulations with 100 IU vs. 150 IU recombinant FSH as starting dose

PURPOSE

To test the possibility of stimulating ovaries with a mild IVF approach using a GnRH agonist long protocol.

METHODS

Retrospective study of 142 first IVF cycles of women aged 30 to 35 who had undergone stimulation with 100 IU or 150 IU of rFSH.

RESULTS

The mean dose of rFSH used was smaller in the low dose compared with the high dose group (999 vs. 1343 IU; p<0.001), obtaining comparable numbers of mature oocytes in both groups. Additionally, reducing the mean number of embryos transferred from 1.8 to 1.5 significantly decreased the twin rate in the low dose group while maintaining similar pregnancy rates in both groups.

CONCLUSIONS

It is possible to develop mild IVF using GnRH agonist long protocol in women with good prognosis. A reduced amount of rFSH and fewer transferred embryos allow for lower costs and risks of IVF without compromising the pregnancy rate.

Embryo implantation rates in natural and stimulated assisted reproduction treatment cycles in poor responders

Controlled ovarian stimulation with exogenous gonadotrophins and gonadotrophin-releasing hormone (GnRH) analogues enables the collection of multiple oocytes and subsequent development of multiple embryos. However, interfering with the natural hormonal milieu may decrease the probability of successful embryo implantation due to effects on oocytes and/or endometrium. In order to provide a fair comparison of embryo implantation rates between natural cycles and stimulated cycles, bias caused by the presence of multiple embryos available for transfer in stimulated cycles should be avoided. This retrospective study analysed embryo implantation rates in cycles in which only a single embryo was available for transfer in 304 women who had poorly responded to ovarian stimulation in the previous cycle. Embryo implantation rates with different stimulation protocols were as follows: natural cycle, 20% (6/30); gonadotrophin only, 5.6% (3/54); long GnRH protocol, 3.8% (2/52); co-flare protocol, 1.9% (1/52); microdose flare-up, 15.4% (4/26); GnRH antagonists, 14.4% (13/90). Although the difference was not statistically significant there was a trend towards higher implantation rates with natural cycles in this group of women. Natural cycle IVF may be a reasonable and patient-friendly treatment choice yielding an acceptable outcome for women who are known or anticipated poor responders to ovarian stimulation.

Controlled ovarian stimulation induces a functional genomic delay of the endometrium with potential clinical implications

CONTEXT

Controlled ovarian stimulation induces morphological, biochemical, and functional genomic modifications of the human endometrium during the window of implantation.

OBJECTIVE

Our objective was to compare the gene expression profile of the human endometrium in natural vs. controlled ovarian stimulation cycles throughout the early-mid secretory transition using microarray technology.

METHOD

Microarray data from 49 endometrial biopsies obtained from LH+1 to LH+9 (n=25) in natural cycles and from human chorionic gonadotropin (hCG) +1 to hCG+9 in controlled ovarian stimulation cycles (n=24) were analyzed using different methods, such as clustering, profiling of biological processes, and selection of differentially expressed genes, as implemented in Gene Expression Pattern Analysis Suite and Babelomics programs.

RESULTS

Endometria from natural cycles followed different genomic patterns compared with controlled ovarian stimulation cycles in the transition from the pre-receptive (days LH/hCG+1 until LH/hCG+5) to the receptive phase (day LH+7/hCG+7). Specifically, we have demonstrated the existence of a 2-d delay in the activation/repression of two clusters composed by 218 and 133 genes, respectively, on day hCG+7 vs. LH+7. Many of these delayed genes belong to the class window of implantation genes affecting basic biological processes in the receptive endometrium.

CONCLUSIONS

These results demonstrate that gene expression profiling of the endometrium is different between natural and controlled ovarian stimulation cycles in the receptive phase. Identification of these differentially regulated genes can be used to understand the different developmental profiles of receptive endometrium during controlled ovarian stimulation and to search for the best controlled ovarian stimulation treatment in terms of minimal endometrial impact.

Gene expression profiling of human peri-implantation endometria between natural and stimulated cycles

OBJECTIVE

To investigate the effect of high serum E(2) levels in gonadotropin-stimulated cycles (hCG+7) on the gene expression patterns of human endometrium compared with natural cycles on the seventh day of LH surge (LH+7) and elucidate the underlying molecular changes that may be related to endometrial receptivity.

DESIGN

Observational study.

SETTING

University Hospital.

PATIENTS(S)

Infertile patients with normal menstrual cycles undergoing IVF treatment.

INTERVENTION(S)

Gonadotropin stimulation and endometrial biopsy.

MAIN OUTCOME MEASURE(S)

Gene expression by microarray and quantitative polymerase chain reaction (qPCR).

RESULT(S)

Endometrial samples from natural (n = 5) and stimulated (n = 8) cycles were collected. Patients in the stimulated cycles were classified as moderate (n = 4) or excessive (n = 4) responders if their serum E(2) levels on the day of administration of hCG were <or=20,000 pmol/L or >20,000 pmol/L, respectively. The RNA transcripts were profiled by Affymetrix HG-U133A microarray. Clustering and principal component analysis demonstrated a significant difference (>or=2-fold) in the expression patterns of 411 genes among the three groups. Putative estrogen response elements or progesterone response elements were identified in the promoter regions of 49 differentially expressed genes of diverse biologic functions. The qPCR confirmed the microarray result in 47 endometrial samples.

CONCLUSION(S)

High serum E(2) and/or progesterone modulate the gene expression profiles of human endometrium and may affect endometrial receptivity.