Endometrial pinopodes indicate a shift in the window of receptivity in IVF cycles

Freeze-all can be a superior therapy to another fresh cycle in patients with prior fresh blastocyst implantation failure

Implantation failure has various causes, including impaired uterine receptivity following ovarian stimulation. This retrospective cohort study compared outcomes in patients with prior implantation failure who elected to undergo another fresh cycle versus those who opted for embryo cohort cryopreservation (freeze-all) and subsequent thaw. There were 269 patients with implantation failure following fresh autologous blastocyst transfer opting to undergo a subsequent cycle, with 163 choosing another fresh cycle and 106 electing freeze-all and subsequent thaw. Multiple logistic regression analysis indicated that cohort cryopreservation was associated with greater chance of live birth when compared with another fresh cycle (P < 0.0001). The odds ratio for live birth with freeze-all relative to a fresh cycle was 3.8 (95% CI 2.1-7.2). A second analysis was then performed using cumulative live birth rate as the outcome measure. Multiple logistic regression indicated freeze-all was associated with greater cumulative live birth rate than was a fresh cycle (OR 1.9, 95% CI 1.1-3.3, P = 0.0287). These findings suggest that, following implantation failure with fresh blastocysts, patients have a significantly greater chance of live birth with freeze-all and subsequent thaw than with another fresh cycle.

Exposure of mice to benzo(a)pyrene impairs endometrial receptivity and reduces the number of implantation sites during early pregnancy

Benzo(a)pyrene (BaP) is a ubiquitous environmental pollutant. Studies have demonstrated it to be an endocrine-disrupting chemical that can cause adverse effects on the female reproductive system. However, the effect of BaP on early pregnancy has not been reported. We investigated the effect of BaP on endometrial receptivity and embryo implantation. Pregnant mice were dosed with BaP at 0.2, 2 and 20 mg/kg/day from day 1 (D1) to day 5 (D5) of gestation. Exposure to BaP impaired the morphology of the endometrium and decreased the number of implantation sites (p0.2=0.006, p2=0.167, p20=0.003). Levels of estrodiol (p<0.001, for three treatment group compare with control group) and progesterone-4 in plasma were elevated in BaP-treatment groups (p0.2<0.001, p2<0.001, p20=0.032). Expression of estrogen receptor-α was up-regulated (p0.2=0.002, p2=0.131, p20=0.024) whereas expression of the progesterone receptor was down-regulated (p0.2<0.001, p2=0.064, p20=0.021). Levels of receptivity-related genes HoxA10 (p0.2<0.001, p2=0.135, p20<0.001) and E-cadherin (p0.2=0.002, p2=0.624, p20=0.137) were changed by BaP. These results revealed that BaP can disrupt the balance of estrogen and progesterone, influence expression of their receptors and downstream related genes, lead to changes in endometrium receptivity, and reduce of the number of implantation sites.

Matrix metalloproteinases 2 and 9 and e-cadherin expression in the endometrium during the implantation window of infertile women before in vitro fertilization treatment

OBJECTIVE

To evaluate the expression of endometrial matrix metalloproteinases (MMPs) 2 and 9 and E-cadherin in peri-implantation phase of infertile women who have undergone in vitro fertilization (IVF) cycles.

METHODS

This prospective study included 51 patients who underwent endometrial biopsy during the receptive phase in a menstrual cycle prior to IVF treatment. The samples were evaluated by tissue microarray for immunohistochemical study.

RESULTS

The expression of MMP-2, MMP-9, and E-cadherin in the endometrium prior to IVF treatment was not associated with pregnancy. There was a decrease in E-cadherin immunodetection, the higher the age of the patients, a negative relationship between E-cadherin and MMP-2, and a positive association between MMP-9 and E-cadherin.

CONCLUSIONS

The MMP-2, MMP-9, and E-cadherin are expressed in the endometrium of infertile patients during the receptive phase of the natural menstrual cycle. However, there is no correlation between the expression of these molecules and the clinical IVF outcomes.

Premature formation of nucleolar channel systems indicates advanced endometrial maturation following controlled ovarian hyperstimulation

STUDY QUESTION

Is there a shift in the timing of nucleolar channel system (NCS) formation following controlled ovarian hyperstimulation (COH)?

SUMMARY ANSWER

NCSs appear prematurely following COH compared with natural cycles.

WHAT IS KNOWN ALREADY

During natural cycles, NCSs of endometrial epithelial cell (EEC) nuclei are exclusively present during the window of implantation and are uniformly distributed throughout the upper endometrial cavity.

STUDY DESIGN, SIZE, DURATION

Prospective two-cohort study. Cohorts I and II each consisted of seven volunteers for the duration of three menstrual study cycles that were separated by at least one wash-out or rest cycle, between December 2008 and May 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were recruited from a pool of healthy oocyte donors. Consecutive endometrial biopsies were obtained during the same luteal phase on cycle days (CD) 16, 20 and 26 for Cohort I, and on CD14, 22 and 24 for Cohort II, following random assignment to a natural cycle group, a COH cycle group (using a GnRH antagonist), or a COH cycle group receiving luteal phase hormonal supplementation (COH + S). The day of oocyte retrieval was designated CD14 in COH cycles and the day of the LH surge was designated CD13 in natural cycles. Prevalence of NCSs in the nuclei of EECs was quantified using indirect immunofluorescence with an antibody directed against a subset of related nuclear pore complex proteins that are major constituents of NCSs. Progesterone and estradiol levels were measured on the day of each endometrial biopsy.

MAIN RESULTS AND THE ROLE OF CHANCE

The natural cycle group exhibited peak NCS prevalence on CD20 [53.3%; interquartile range (IQR) 28.5-55.8], which rapidly declined on CD22 (11.8%; IQR 6.3-17.6), CD24 (2.5%; IQR 0.0-9.2) and CD26 (0.3%; IQR 0.0-3.5), and no NCSs on CD14 and 16 defining a short NCS window around CD20. In contrast, in COH and COH + S cycles, NCS prevalence was high already on CD16 (40.4%; IQR 22.6-53.4 and 35.6%; IQR 26.4-44.5, respectively; P = 0.001 compared with CD16 of the natural cycle group, Mann-Whitney), whereas no significant difference in NCS prevalence was detected on any of the other five CDs between the three groups (P > 0.05).

LIMITATIONS, REASONS FOR CAUTION

The cohort size was small (n = 7) but was offset by the all-or-none presence of NCSs on CD16 in natural versus COH and COH + S cycles and the fact that each subject served as her own control.

WIDER IMPLICATIONS OF THE FINDINGS

Premature appearance of NCSs and hence maturation of the endometrium following COH is consistent with previous studies based on histological dating but contradicts studies based on mRNA expression profiling, which reported a lag in endometrial maturation. However, this is the first study of this kind that is based on consecutive endometrial biopsies within the same cycle and that reports such clear-cut differences: no versus robust NCS presence on CD16. Our observation of advanced endometrial maturation following COH may contribute to the reduced implantation rates seen in fresh compared with frozen and donor IVF-embryo transfer cycles. Therefore, the NCS window could serve as a sensitive guide for timing of embryo transfer in frozen and donor cycles.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the March of Dimes Birth Defects foundation (1-FY09-363 to U.T.M.); Ferring Pharmaceuticals, Parsippany, NJ; East Coast Fertility, Plainview, NY and the CMBG Training Program (T32 GM007491 to M.J.S.). We report no competing interests.

Ovulation induction and epigenetic anomalies

In this systematic review of ovulation induction and epigenetic control, studies mainly done in the mouse model highlight how hormone treatments may be prejudicial to the epigenetic reprogramming of gametes as well as early embryos. Moreover, the hormone protocols used in assisted reproduction may also modify the physiologic environment of the uterus, a potential link to endometrial epigenetic disturbances. At present, the few available data in humans are insufficient to allow us to independently determine the impact of a woman's age and infertility problems and treatment protocols and hormone doses on such processes as genomic imprinting.

The luteal phase after ovarian stimulation

Evaluation of the luteal phase after ovarian stimulation presents several difficulties. Until today, it has not been proved that in cycles stimulated with clomiphene citrate/human menopausal gonadotrophins, luteal supplementation with progesterone significantly increases implantation rate. On the contrary, it is accepted that in cycles stimulated with GnRH agonists/gonadotrophins, support of the luteal phase is essential for the achievement of pregnancy. In GnRH antagonist cycles luteal supplementation, although widely practised, is not at present supported by randomized controlled trials. Finally, it appears that the combination of gonadotrophin stimulation with human chorionic gonadotrophin results in an inadequate luteal phase with or without the use of either agonists or antagonists.

Effect of the site of assisted hatching on vitrified-warmed blastocyst transfer cycles: a prospective randomized study

PURPOSE

To assess the effect of assisted hatching (AH) site on the clinical outcomes in vitrified-warmed blastocyst transfer cycles.

METHODS

A total of 160 women who underwent vitrified-warmed blastocyst transfer cycles were randomized to either the ICM group (AH performing at the site near the inner cell mess, ICM), or the TE group (AH performing at the site opposite to the ICM). AH with laser zona drilling was performed 20 or 30 min after thawing once the ICM can be detected. Clinical pregnancy rate, implantation rate, live birth rate and the occurrence rate of monozygotic twins (MZT) pregnancy after transfer of these two groups were compared.

RESULTS

No significant difference was found in the clinical pregnancy rate (63.8% vs. 67.5%), implantation rate (51.7% vs. 53.6%) and live birth rate (57.5% vs. 62.5%) between the ICM group and the TE group. The occurrence rate of MZT was comparable between the two groups (3.9% vs. 5.6%).

CONCLUSIONS

The site of assisted hatching has no influence on the implantation, pregnancy and live birth rate in human vitrified-warmed blastocyst transfer cycles.

Effects of DEHP on endometrial receptivity and embryo implantation in pregnant mice

Di-(2-ethylhexyl)-phthalate (DEHP) is a ubiquitous environmental pollutant and endocrine disruptor (ED) that causes serious adverse effects on animal and human health. The harmful effects of DEHP on human reproduction are increasingly recognized, especially in women. However, it is not known how endometrial receptivity and embryo implantation, which play important roles in the establishment of pregnancy, are affected by DEHP. This study was aimed towards investigating the effects of DEHP on endometrial receptivity and embryo implantation in pregnant mice. The pregnant mice received DEHP at 0, 250, 500 and 1000 mg/kg/day from day 1 (D1) of gestation until sacrifice. Administration of DEHP led to compromised endometrial receptivity and decreased number of implantation sites. The mRNA and protein expression levels of ERα, PR and E-cadherin, but not those of HoxA10 and MMP-2, were up-regulated by DEHP in the mouse endometrium. The results further suggested that DEHP disrupts the MAPK and NF-κB signaling pathways. This was maybe one of paths which influenced the E-cadherin expression. In conclusion, DEHP reduced endometrial receptivity and impaired embryo implantation by influencing the expression of hormone receptors and E-cadherin. Therefore, determining the full extent of the hazards of DEHP to human reproduction will be vital to developing and implementing effective protective measures.

Vitrification can modify embryo cleavage stage after warming. Should we change endometrial preparation?

PURPOSE

Studies have shown that embryo metabolism and cell cleavage after warming vitrified embryos is faster than after thawing frozen embryos. We study vitrified embryo transfer (VET) results depending on the developmental stage of warmed embryos and the duration of progesterone treatment before embryo transfer.

METHODS

We designed a prospective study, patients were randomized in two groups, starting progesterone three (D + 3) or four days (D + 4) before embryo transfer. We recruited 88 patients with embryos vitrified on day 3.

RESULTS

We didn't find statitistical differences in pregnancy rate when we transferred embryos in D + 3 vs D + 4 (38.2 % vs 40.5 % p ≥ 0.05). The day after warming, 54.6 % of embryos had developed to morula or early blastocyst, 32.4 % to cleavage stage and 13 % didn't cleave. Transfers were with morula/blastocysts stage embryos (52.1 %; n:37), cleavage stage embryos (18.3 %; n:13) or mixed (29.6 %; n:21). Implantation rate was significantly higher in morula/blastocyst stage than in cleavage stage or mixed transfers (44 %, 22 % and 16.3 %; p = 0.011). Pregnancy and implantation rates were significantly higher in morula/blastocyst transfers on D + 4 than on D + 3 (68.7 % and 64.7 % vs 33.3 %, and 33.3 %, p = 0.033 and p = 0.034).

CONCLUSIONS

Our findings suggest that a majority of embryos will develop to morula/blastocyst stage after warming. VET results with morula/blastocysts, and after four days of progesterone supplementation, are better than with cleavage stage embryos.

Deciphering the molecular basis of uterine receptivity

Uterine receptivity is defined as a limited time period during which the uterus enters into an appropriately differentiated state that is ready for the initiation of implantation by competent blastocysts. Although various cellular aspects and molecular pathways involved in uterine receptivity have been identified by gene expression studies and genetically engineered mouse models, a comprehensive understanding of the window of uterine receptivity is still missing. This review focuses on the recent progress in this area, with particular focus on the molecular basis of stromal-epithelial dialogue and crosstalk between the blastocyst and the uterus during implantation. A better understanding of the underlying mechanisms governing the window of uterine receptivity is hoped to generate new strategies to correct implantation failure and to improve pregnancy rates in women.

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.

Progesterone support in IVF: is evidence-based medicine translated to clinical practice? A worldwide web-based survey

This worldwide web-based survey compared the clinical practice for luteal-phase supplementation (LPS) in stimulated IVF cycles to the current evidence-based literature. Eighty-four treatment centres in 35 countries, representing a total of 51,155 IVF cycles/year, responded. Vaginal progesterone alone was used for LPS in 64% of cycles and in another 16% of cycles in combination with either i.m. (15%) or oral progesterone (1%). As a single agent, i.m. progesterone was used in 13% of cycles, oral progesterone in another 2% and human chorionic gonadotrophin (HCG) was still used in 5% of cycles. Progesterone was administered until 10-12 weeks' gestation in 67% of cycles and in 22% and 12% it was discontinued when fetal heart pulsations are recognized or until βHCG was positive, respectively. In conclusion, in almost two-thirds of the assisted cycles represented in this survey, vaginal administration of progesterone is preferred for LPS. Nevertheless, despite the available literature on the disadvantages of oral progesterone, i.m. progesterone and HCG for LPS, these agents are still used routinely by many practitioners. Furthermore, although there is no firm evidence to support the continuation of LPS until 10-12 weeks' gestation, this practice is used in the majority of IVF cycles worldwide.

Expression pattern of osteopontin and αvβ3 integrin during the implantation window in infertile patients with early stages of endometriosis

BACKGROUND

To study endometrial receptivity in terms of osteopontin (OPN) and αvβ3 integrin expression and co-expression in infertile women with early stages of endometriosis.

METHODS

We investigated the immunohistochemical expression and co-expression of OPN and αvβ3 integrin in the endometrium of 20 infertile patients with Stage I or II endometriosis as the only detectable cause of infertility, 20 infertile patients with unexplained infertility and 20 fertile women undergoing tubal sterilization. Two endometrial biopsies were performed during a single menstrual cycle (postovulatory Day +7 to +8 and 4 days later) in each subject.

RESULTS

No statistically significant differences regarding OPN and αvβ3 integrin expression were found between infertile patients with endometriosis and the two control groups. There was no significant correlation between OPN and αvβ3 integrin staining intensity in the mid-luteal phase biopsies in any of the groups studied.

CONCLUSIONS

Endometrial OPN and αvβ3 integrin expression or co-expression is not impaired during the window of implantation in patients with Stage I-II endometriosis. Further studies are needed to determine whether these results imply normal endometrial receptivity in such patients or add to the increasing uncertainty about the clinical value of assessing the endometrium with these markers of implantation.

Assessment of endometrial receptivity

OBJECTIVE

To provide a focused review of the scientific literature pertaining to endometrial receptivity.

DESIGN

Review of the literature and appraisal of relevant articles.

SETTING

Academic teaching hospital.

PATIENT(S)

Women with infertility.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Critical review of the literature.

RESULT(S)

Although a consensus has been achieved regarding the existence of a temporally defined period during which embryo attachment and invasion can occur (called the "window of implantation"), reliable methods to assess "receptivity" have not been established or adequately validated. In women with certain gynecologic disorders, including endometriosis, tubal disease, and polycystic ovary syndrome, endometrial receptivity seems to be compromised, leading to infertility and pregnancy loss. The establishment of reliable biomarkers for the detection of defects in endometrial receptivity has been a long-sought goal that remains an elusive target. The validation of endometrial biomarkers will require properly designed and implemented studies based on the recognition that endometrial receptivity defects are not equally distributed in women with endometriosis or these other conditions.

CONCLUSION(S)

Rapidly advancing technologies are bringing new biomarkers to the clinical arena that promise to further reveal the complexities of the implantation process.

Evidence of impaired endometrial receptivity after ovarian stimulation for in vitro fertilization: a prospective randomized trial comparing fresh and frozen-thawed embryo transfers in high responders

Clinical pregnancy rates of 80% and 65% were observed in cycles using thawed and fresh embryos, respectively, although embryo quality indicators revealed morphologically and numerically inferior embryo cohorts after cryopreservation. Subsequent logistic regression analysis controlled for differences in embryo quality and revealed significantly greater probability of clinical pregnancy with thawed embryos when compared with fresh, suggesting a negative effect of ovarian stimulation on endometrial receptivity.

Human endometrium ultrastructure during the implantation window: a new perspective of the epithelium cell types

The human endometrium is a hormonally regulated tissue that cyclically growths and differentiates in order to become a structure adequate for implantation. Molecular studies have shown some contradicting results and thus a reappraisal of the endometrium ultrastructure is warranted. In our study, endometrium biopsies were taken during the implantation window of 10 healthy women of reproductive age and analyzed using electron microscopy. Our results showed that during implantation window, the endometrial epithelium encompassed 4 cell types: microvilli-rich cells, pinopode cells, vesiculated cells, and ciliated cells. These cells showed signs of active communication with their external environment and neighboring cells, such as endocytosis, transcytosis and exocytosis. We highlighted important differences between surface and glandular epitheliums and characterized apocrine and holocrine secretion. It is likely that the features described reflect distinct functions in endometrium physiology that should be taken into account in the evaluation of the endometrium during the implantation window.

MicroRNA array and microarray evaluation of endometrial receptivity in patients with high serum progesterone levels on the day of hCG administration

BACKGROUND

To determine the effect of higher progesterone (P) level on endometrial receptivity.

METHODS

This was a prospective analysis conducted in the Reproductive Medical Center of Peking University Third Hospital. All patients received IVF treatment and canceled embryo transfer in the same cycle and were divided into group 1 (normal P; 7 patients) and group 2 (elevated P; 12 patients). Endometrial biopsies were performed 6 days after oocyte retrieval. The global miRNA and mRNA gene expressions in endometrial biopsies were investigated with a V4.0 miRNA probe and 22 K Human Genome Array. Fold ratios were derived to compare gene regulation between the groups. Spp1 and Ang gene expression was selected to verify the array results by RT-PCR and the protein expression of osteopontin and VEGF was determined using an immunohistochemical method.

RESULTS

There were 4 miRNA (all down-regulated) and 22 mRNA (13 up-regulated and 9 down-regulated) exhibiting differential expression between the groups on the microRNA and microarray chips. miRNA-451, Spp1, and Ang expression in RT-PCR verified the array results. Osteopontin and VEGF were also shown to have positive expression in the endometrium.

CONCLUSIONS

Data from microRNA and microarray analysis suggests dissimilar endometrial receptivity in patients with high P levels on the day of hCG, and elevated osteopontin and decreased VEGF had poor pregnancy rates.

Blastocyst embryo transfer is the primary determinant for improved outcomes in oocyte donation cycles

AIM

Using oocyte donation cycles as an ideal model, we sought to compare pregnancy and implantation rates in cleavage stage (day 3) versus blastocyst stage (day 6) embryo transfers (ET); assess the predictive value of blastocyst formation rates based on cleavage cell stage and morphology grade; and evaluate the ability to predict formation of high quality (HQ) blastocysts.

METHODS

Ninety three consecutive oocyte donation cycles from July 2003 to August 2005 were retrospectively evaluated and analyzed to determine if either resulted in a cleavage stage (n = 30) or blastocyst (n = 45) ET. The primary outcomes measured pregnancy rates, the percent development of HQ blastocysts based on day 3 embryo status, and the ability to select day 3 embryos suitable for transfer among four blinded evaluators by assessing their day 6 embryo outcome.

RESULTS

Cleavage stage ET resulted in significantly lower pregnancy rates, clinical pregnancy rates, and implantation rates (47% [n = 14/30]; 40% [n = 12/30] and 27 + or - 7%) compared to blastocyst stage (82% [n = 37/45]; 73% [n = 33/45] and 64 + or - 6% [+ or -SE], P < 0.01). In total, HQ blastocysts resulted from high and good quality day 3 embryos 35% (191/546) and 17% (93/546), respectively. Blinded evaluation revealed at least one, two or all three day 3 embryos were correctly selected for ET on day 6, 97%, 67% and 19%, respectively.

CONCLUSION

Day 6 ET resulted in significantly better clinical outcomes compared to day 3 ET. While day 3 status is not predictive of blastocyst quality, the selection of at least one day 3 embryo ultimately suitable for blastocyst ET underscores the significance of optimal endometrial receptivity.

Ovarian stimulation retards postimplantation development and alters global gene expression profile of blastocysts in mouse

This study compares the quality, developmental capacity and global gene expression profile of embryos generated from superovulated and natural cycles. We found that ovarian stimulation impaired quality of blastocysts (cell number: 68.9 +/- 6.9 vs. 76.8 +/- 7.9; diameter of blastocysts: 145.3 +/- 76.9 microm vs. 152.6 +/- 65.5 microm), fetus development (rate of development to term: 45.5% vs. 69.1%; weight of 18.5-dpc fetuses: 1.23 +/- 0.03 g vs. 1.34 +/- 0.03 g) and caused 92 genes differentially expressed.

High serum oestradiol concentrations in IVF cycles increase the risk of pregnancy complications related to abnormal placentation

The study was designed to evaluate the isolated effect of high serum oestradiol concentration on human chorionic gonadotrophin (HCG) day in IVF cycles on endometrial receptivity and placentation. A retrospective cohort included all women attending the IVF unit in 2006 and 2007, with the best prognosis to achieve pregnancy: age (<38 years), less than three IVF cycles, transfer of two highest grade embryos and no evidence of factors known to impair implantation or that are associated with increased risk of pregnancy complications. The total included 280 patients were categorized into three groups according to their serum oestradiol concentration on HCG day: group 1, oestradiol <5000 pmol/l, group 2, oestradiol in the range 5000-10,000 pmol/l and group 3, oestradiol in the range of 10,000-15,000 pmol/l. No significant differences were found between the groups in implantation, pregnancy and abortion rates. The high oestradiol group was characterized by high rate (20.8%) of pregnancy complications related to abnormal placentation--fetal growth restriction, pregnancy-induced hypertension and abnormal implantation of the placenta. Hence, the decision to perform embryo transfer in high-responder patients should take into consideration both possible risks of ovarian hyperstimulation syndrome and pregnancy complications related to abnormal placentation.

Efficacy and safety of long-acting GnRH agonists in in vitro fertilization and embryo transfer

The introduction of gonadotrophin-releasing hormone (GnRH) agonists combined with gonadotrophins is considered to be one of the most significant events in the development of in vitro fertilization and embryo transfer (IVF-ET) programmes. This article reviews the use of GnRH agonists in IVF-ET programmes and the efficacy and safety of long-acting GnRH agonists. The use of agonists results in higher clinical pregnancy rates, more supernumerary embryos for cryopreservation and allows convenient programming of oocyte recovery. There are different types of agonist and ovarian stimulation protocol available for clinical use. Recent meta-analysis of the Cochrane database has demonstrated the superiority of the long protocols over the short and ultra-short protocols for GnRH agonist use in IVF and GIFT. The depot injection offers increased clinical and patient compliance and improves efficacy of pituitary downregulation. However, compared with short-acting agonists, the depot preparations are associated with a longer period of stimulation and higher doses of gonadotrophins. To date, there is no evidence of an increased risk of pregnancy wastages or teratogenicity in human pregnancies exposed to long-acting agonists.

Protein profile of the luteal phase endometrium by tissue microarray assessment

To investigate the luteal phase endometrial expression of leukemia inhibitor factor (LIF), insulin-like growth factor 1 (IGF-1), progesterone receptor (PR), claudin 4 (CLDN4), vascular-endothelial growth factor receptor 3 (VEGFR-3), bone morphogenetic protein 4 (BMP-4) and citokeratin 7 (CK-7), we obtained luteal phase endometrial samples from 52 women. Samples were dated and integrated using a tissue microarray (TMA). Samples were immunostained for LIF, IGF-1, PR, CLDN4, VEGFR-3, BMP-4 and CK-7. Frequencies of positive expressions at the early, mid and late luteal phases were compared by two proportions test. Concomitant expression of these proteins was assessed with Chi-square or Fischer's test. The frequency of LIF was positively correlated to the frequency of IGF-1 (r = 0.99; p < 0.05) and PR (r = 0.99; p < 0.05), and the correlation between IGF-1 and PR tended to be significant (r = 0.98; p < 0.1). The expression of PR was associated with the absence of CLDN4 (p < 0.001). Thus, expression of LIF, IGF-1 and PR are correlated during the luteal phase, and immunohistochemistry for these proteins might be used to assist in the assessment of endometrial maturation. In addition, the expression of CLDN4 and PR was not concomitant, warranting further investigation on the relationship of their endometrial expression.

Serum estradiol levels during controlled ovarian hyperstimulation influence the pregnancy outcome of in vitro fertilization in a concentration-dependent manner

OBJECTIVE

To determine an optimal serum E(2) level on the day of hCG administration in controlled ovarian hyperstimulation (COH) during IVF-ET without compromising pregnancy outcome.

DESIGN

Retrospective study.

SETTING

Large urban medical center.

PATIENT(S)

Data of 455 cycles of fresh IVF-ET with COH.

INTERVENTION(S)

Serum E(2) levels on the day of hCG administration were categorized into five groups: group A (<1000 pg/mL), group B (1000-2000 pg/mL), group C (2000-3000 pg/mL), group D (3000-4000 pg/mL), and group E (>4000 pg/mL).

MAIN OUTCOME MEASURE(S)

Serum E(2) levels, number of oocytes retrieved, pregnancy outcomes.

RESULT(S)

Of 455 cycles, 148 (32.5%) cycles resulted in clinical pregnancy. The implantation rate was 12.2%, and the delivery rate was 18.7%. The number of oocytes obtained increased with increasing serum E(2) levels. The pregnancy rate gradually increased from group A to D as E(2) levels increased but decreased in group E. In women <38 years, the IVF-ET outcomes were similar to those of total patients. However, in women >/=38 years old, pregnancy and delivery rates were higher in group C than in other groups.

CONCLUSION(S)

These results show that serum E(2) levels have a concentration-dependent effect on the pregnancy outcome, suggesting an optimal range of E(2) level for achieving a successful pregnancy. This optimal range of serum E(2) level in women is age dependent: 3000-4000 pg/mL for women <38 years and 2000-3000 pg/mL for women >/=38 years.

Embryo cryopreservation rescues cycles with premature luteinization

OBJECTIVE

To determine whether embryo cryopreservation in cycles with elevated preovulatory P followed by thaw, extended culture, and transfer results in greater ongoing pregnancy rates than fresh blastocyst transfer.

DESIGN

Retrospective matched cohort study.

SETTING

Private fertility center.

PATIENT(S)

The study group consisted of 118 consecutive thaws of bipronucleate (2PN) oocytes derived from autologous cycles with elevated preovulatory P, resulting in 95 blastocyst transfers. The control group was selected by matching on the number of 2PN oocytes and patient age and consisted of 118 fresh cycles with elevated preovulatory P, including 108 fresh autologous blastocyst transfers. All patients were <41 years old at the time of stimulation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Implantation and ongoing pregnancy rates.

RESULT(S)

The study group had significantly fewer blastocysts per 2PN oocyte than the control group (19.7% vs. 36.8%, respectively) and a significantly greater cancellation rate (19.5% vs. 8.5%, respectively). However, the ongoing pregnancy rate per cycle was significantly higher in the study group than in the control group (56.8% vs. 32.2%, respectively), resulting from greater rates of implantation (56.8% vs. 26.9%, respectively) and of ongoing pregnancy per transfer (70.5% vs. 35.2%, respectively).

CONCLUSION(S)

In cycles with elevated preovulatory P, the probabilities of implantation and ongoing pregnancy are increased if all 2PN oocytes are cryopreserved and subsequently thawed and cultured to the blastocyst stage before transfer.

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.

The role of steroid hormones in ART

Steroid hormones hold a major role in female fertility and their proper utilisation and monitoring in modern assisted reproduction protocols is important. Oocyte maturation and endometrial receptivity are the two major factors that appear to be related to a successful outcome in Assisted Reproductive Technology (ART). Many reports suggest that oocyte immaturity accounts for a considerable loss of efficiency in ART, mainly due to the poor quality of the obtained embryos and their inability to develop normally. Oestrogen appears to exert its effects on the cytoplasmic maturation of the oocyte, while progesterone has been shown to accelerate meiotic resumption. Moreover, ovarian stimulation appears to affect the normal luteal function and shifts in the window of implantation as a response to hormonal supplementation have also been observed. The ethical limitations in conducting in vivo studies of human implantation, have led to an indirect hormonal- and morphologic-oriented assessment of endometrial receptivity. The two main protocols of luteal support involve either progesterone supplementation or hCG administration, whereas the combined supplementation with oestradiol remains controversial. This brief review aims to summarize the current knowledge on steroidal actions during the above processes and to address their potential use in the improvement of current ART protocols.

An integrated view of L-selectin and trophinin function in human embryo implantation

Determining molecular mechanisms of human embryo implantation is an extremely challenging task due to the limitation of materials and significant differences underlying this process among mammalian species. Recently, L-selectin and its ligand carbohydrate have been proposed as a system that mediates initial adhesion of human blastocysts to the uterine epithelia. We have also identified trophinin as a unique apical cell adhesion molecule potentially involved in the initial adhesion of trophectoderm of the human blastocyst to endometrial surface epithelia. In the mouse, the binding between ErbB4 on the blastocyst and heparin-binding epidermal growth factor-like growth factor on the endometrial surface enables the initial step of the blastocyst implantation. The evidence suggests that L-selectin and trophinin are included in human embryo implantation. This review summarizes findings relevant to the functions of L-selectin and trophinin in human embryo implantation, and proposes a model that reconciles these cell adhesion mechanisms.

Large blastocyst diameter, early blastulation, and low preovulatory serum progesterone are dominant predictors of clinical pregnancy in fresh autologous cycles

OBJECTIVE

To identify dominant predictors of clinical pregnancy in IVF cycles.

DESIGN

Retrospective study.

SETTING

Private fertility center.

PATIENT(S)

The study included 580 fresh autologous IVF cycles with blastocyst transfer.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate.

RESULT(S)

A set of 25 suspected predictors was used to develop predictive models of clinical pregnancy in a set of 361 blastocyst transfer cycles. Initial bivariate analysis identified 14 of these variables that were significant enough to be candidate variables for multiple logistic regression. Similar sets of significant variables were identified by using alternative approaches for model construction. The final model included blastocyst diameter, day of blastulation, and preovulatory serum P level as significant predictors of clinical pregnancy. Specifically, clinical pregnancy was predicted by preovulatory serum P of <1.0 ng/mL, blastulation on day 5, and large blastocyst diameter. Of these variables, blastocyst diameter was the most significant predictor of clinical pregnancy in the multivariate models. The final model was validated against a separate set of 219 subsequent blastocyst transfer cycles.

CONCLUSION(S)

Pre-ovulatory serum P level, blastulation day, and embryo diameter are simultaneously predictive of clinical pregnancy, and their relationships with clinical pregnancy are consistent with an effect of embryo-endometrium synchrony.

Impact of assisted hatching on fresh and frozen-thawed embryo transfer cycles: a prospective, randomized study

The aim of this study was to determine if assisted hatching (AH) could improve the rates of pregnancy and implantation for both fresh and frozen-thawed embryo transfer cycles. A total of 760 fresh embryo transfer cycles and 200 frozen-thawed embryo transfer cycles were randomly assigned to either the treatment group (AH) or the control group (no AH). Zona thinning by laser was performed just before embryo transfer. In fresh embryo transfer cycles, the AH group and control group results were comparable. There were no significant differences in the rates of positive human chorionic gonadotrophin (HCG; 47.5 versus 48.8%), clinical pregnancy (42.4 versus 42.6%), or implantation (26.3 versus 25.2%) between the two groups. However, in frozen-thawed embryo transfer cycles, the rates of positive HCG (32.0 versus 17.0%), clinical pregnancy (25.0 versus 14.0%) and implantation (16.7 versus 7.3%) were significantly greater in the AH group than in the control group (P &lt: 0.05). The results of this investigation show that in the fresh embryo transfer cycles, laser-assisted hatching by zona thinning has no impact on the rates of positive HCG, clinical pregnancy and implantation, whereas in frozen-thawed cycles, assisted hatching by zona thinning significantly increases all three of these rates.

Elective cryopreservation of all day 5 blastocysts is more effective than using day 6 blastocysts for improving pregnancy outcome in stimulated cycles

Aim:  To evaluate the efficacy of cryopreservation of all blastocysts for future transfers in stimulated cycles. Methods:  We carried out fresh blastocyst transfer cycles on day 5 (n = 290) or day 6 (n = 119) and thawed blastocyst transfer cycles that were frozen on day 5 (n = 136), day 6 (n = 71) or day 6 electively (n = 21). We retrospectively compared the clinical outcome of fresh blastocyst transfers with thawed blastocyst transfers according to the day of blastocyst transfer or freezing. Results:  The clinical implantation rates in women with stimulated cycles were significantly higher after the transfer of thawed blastocysts compared with the transfer of fresh blastocysts (day 5, P < 0.0005; day 6, P < 0.00005). Although the implantation rate of fresh day 6 transfer cycles was lower than that of elective day 6 frozen-thawed cycles, this difference was not statistically significant (P = 0.17). Conclusions:  Thawed blastocysts demonstrated a better potential for implantation when compared with fresh blastocysts in stimulated cycles. We concluded that elective cryopreservation of all blastocysts on day 5 is an effective option to improve the clinical outcome in stimulated cycles. Additionally, with cryopreservation of all day 6 blastocysts, the implantation rates of first embryo transfers may increase by allowing the best-quality blastocysts to be transferred in thawed cycles. (Reprod Med Biol 2008; 7: 75-83).

Uterine receptivity to human embryonic implantation: histology, biomarkers, and transcriptomics

Embryonic implantation is a dynamic process of paracrine interactions between the maternal compartment and the conceptus and involves a receptive endometrium and a developmentally competent blastocyst. Herein, we review histology, clinical approaches, and the promise of transcriptomics in elucidating mechanisms underlying implantation and development of biomarkers of uterine receptivity-with an eye to diagnose and treat implantation-based disorders of miscarriage, fetal growth restriction, pre-eclampsia, and infertility.

Endometrial leukemia inhibitory factor as a predictor of pregnancy after in vitro fertilization

OBJECTIVE

To determine whether there is an association between endometrial expression of leukemia inhibitory factor (LIF) in the luteal phase of the menstrual cycle preceding in vitro fertilization (IVF) and treatment outcome.

METHODS

Biopsy specimens from the endometria of 52 women in the luteal phase were immunostained against LIF. Embryo culture and transfer were done according to standard procedures.

RESULTS

Clinical pregnancy occurred in 39% of the women following IVF, and strong endometrial immunohistochemical staining for LIF was associated with pregnancy (P=0.01). The women with a strong LIF expression had a 6.4-fold higher chance of becoming pregnant than those with weaker intensities (P=0.005).

CONCLUSION

Endometrial expression of LIF during the luteal phase can be used as a predictor of IVF success.

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.