Developmental stage and morphology of the competent blastocyst are associated with sex of the child but not with other obstetric outcomes: a multicenter cohort study.

STUDY QUESTION: Are transfer day, developmental stage and morphology of the competent blastocyst in pregnancies leading to live birth associated with preterm birth, birthweight, length at birth and sex of the child? SUMMARY ANSWER: A high score in blastocyst developmental stage and in trophectoderm (TE) showed a significant association with the sex of the child, while no other associations with obstetric outcomes were observed. WHAT IS KNOWN ALREADY: The association between blastocyst assessment scores and obstetric outcomes have been reported in small single-center studies and the results are conflicting. STUDY DESIGN, SIZE, DURATION: Multicenter historical cohort study based on exposure data (transfer day (blastocyst developmental stage reached by Day 5 or Day 6)) blastocyst developmental stage (1-6) and morphology (TE and inner cell mass (ICM): A, B, C)) and outcome data (preterm birth, birthweight, length at birth, and sex of the child) from women undergoing single blastocyst transfer resulting in a singleton pregnancy and live birth. PARTICIPANTS/MATERIALS, SETTING, METHODS: Data from 16 private and university-based facilities for clinical services and research were used. A total of 7246 women, who in 2014-2018 underwent fresh-embryo transfer with a single blastocyst or frozen-thawed embryo transfer (FET) with a single blastocyst resulting in a singleton pregnancy were identified. Linking to the Danish Medical Birth Registry resulted in a total of 4842 women with a live birth being included. Cycles with pre-implantation genetic testing and donated gametes were excluded. The analyses were adjusted for female age (n = 4842), female BMI (n = 4302), female smoking (n = 4290), parity (n = 4365), infertility diagnosis (n = 4765), type of treatment (n = 4842) and center (n = 4842); some analyses additionally included gestational age (n = 4368) and sex of the child (n = 4833). MAIN RESULTS AND THE ROLE OF CHANCE: No statistically significant associations between blastocyst assessment scores (transfer day, developmental stage, TE, ICM) and preterm birth (8.3%) or birthweight (mean 3461.7 g) were found. The adjusted association between blastocysts with a TE score of C and a TE score of A and length at birth (mean 51.6 cm) were statistically significant (adjusted mean difference 0.4 cm (95% CI: 0.02; 0.77)). Blastocysts transferred with developmental stage score 5 compared to blastocysts transferred with score 3 had a 34% increased probability of being a boy (odds ratio (OR) 1.34 (95% CI: 1.09; 1.64). Further, TE score B blastocysts compared to TE score A blastocysts had a 31% reduced probability of being a boy (OR 0.69 (95% CI: 0.60; 0.80)). LIMITATIONS, REASONS FOR CAUTION: It is possible that some residual confounding remains. WIDER IMPLICATIONS OF THE FINDINGS: Blastocyst selection during ART does not appear to introduce any negative effects on obstetric outcome. Therefore, clinicians and patients can be reassured that the assessment scores of the selected blastocyst will not in themselves pose a risk of preterm birth or affect birthweight and the length at birth. STUDY FUNDING/COMPETING INTEREST(S): Unrestricted grant from Gedeon Richter Nordics AB, Sweden. None of the authors have any competing interest to declare. TRIAL REGISTRATION NUMBER: N/A.

A multi-centre phase 3 study comparing efficacy and safety of Bemfola(®) versus Gonal-f(®) in women undergoing ovarian stimulation for IVF.

Bemfola (follitropin alfa) (Finox AG, Switzerland), a new recombinant FSH, has a comparable pharmacological profile to that of Gonal-f (Merck Serono, Germany), the current standard for ovarian stimulation. A randomized, multi-centre, Phase 3 study in women undergoing IVF or intracytoplasmic sperm injection (n = 372) showed Bemfola yielding similar efficacy and safety profiles to Gonal-f. Women aged 20-38 years of age were randomized 2:1 to receive a single, daily, subcutaneous 150 IU dose of either Bemfola or Gonal-f. This study tested equivalence in the number of retrieved oocytes using a pre-determined clinical equivalence margin of ±2.9 oocytes. Compared with Gonal-f, Bemfola treatment resulted in a statistically equivalent number of retrieved oocytes (Bemfola 10.8 ± 5.11 versus Gonal-f 10.6 ± 6.06, mean difference: 0.27 oocytes, 95% confidence interval: -1.34, 1.32) as well as a similar clinical pregnancy rate per embryo transfer in first and second cycles (Bemfola: 40.2% and 38.5%, respectively; Gonal-f: 48.2% and 27.8%, respectively). No difference in severe ovarian hyperstimulation syndrome was observed between treatment groups (Bemfola: 0.8%; Gonal-f: 0.8%). This study demonstrates similar clinical efficacy and safety profiles between Bemfola and Gonal-f, and suggests that Bemfola can be an appropriate alternative in ovarian stimulation protocols.

Mifepristone, but not levonorgestrel, inhibits human blastocyst attachment to an in vitro endometrial three-dimensional cell culture model.

BACKGROUND: The use of fertility regulating drugs is limited among various socio-ethnic groups due to limited knowledge about their mechanism of action. This study investigates the effect of levonorgestrel and mifepristone on attachment of human embryos to an in vitro endometrial construct. METHOD: Three-dimensional endometrial constructs were established by co-culturing early luteal phase human endometrial stromal and epithelial cells. Expression of endometrial receptivity markers in this construct were examined by immunohistochemistry. Effects of mifepristone and levonorgestrel on viability and attachment of human blastocysts were investigated. RESULTS: Endometrial constructs expressed the factors involved in endometrial receptivity: estrogen receptor, progesterone receptor, vascular endothelial growth factor, leukemia inhibitory factor, interleukin-1, COX-2, MUC-1 and integrin-alpha(V)beta(3). None of the 15 embryos cultured with mifepristone attached to the endometrial construct (P < 0.01), whereas 10/17 in control, and 6/14 in levonorgestrel, groups attached. The attachment was confirmed by the positive expression of cytokeratin 7 at the attachment site. CONCLUSION: Mifepristone inhibits blastocyst attachment. Levonorgestrel did not impair the attachment of human embryos to the in vitro endometrial construct. This model could be used to understand endometrial receptivity and embryo-endometrial dialog and to develop new fertility regulating substances.

Implantation of the human embryo: research lines and models. From the implantation research network 'Fruitful'.

Infertility is an increasing problem all over the world, and it has been estimated that 10-15% of couples in fertile age have fertility problems. Likewise induced unsafe abortion is a serious threat to women's health. Despite advances made in assisted reproduction techniques, little progress has been made in increasing the success rate during fertility treatment. This document describes a wide range of projects carried out to increase the understanding in the field of embryo implantation research. The 'Fruitful' research network was created to encourage collaborations within the consortium and to describe our different research potentials to granting agencies or private sponsors.

Relevance of endometrial pinopodes for human blastocyst implantation.

Endometrial pinopodes, hormone-dependent protrusions of the endometrial apical plasma membrane, have been suggested as indicators of endometrial receptivity. The lifespan of endometrial pinopodes appears to be tightly regulated. Interestingly, considerable interpatient variations according to the onset of pinopode formation have been observed. In normal fertile women, pinopodes are present on days 6-8 post-ovulation, whereas pinopode formation is observed 1-2 days earlier in patients undergoing controlled ovarian hyperstimulation. In oocyte recipients treated with oestradiol and progesterone in hormone-controlled cycles, pinopode formation seems to be delayed. In-vitro experimental studies on human blastocyst attachment to an artificial endometrium indicate a preference for human blastocysts to attach to pinopode presenting areas on the endometrial surface. Transmission electron microscopy shows that the blastocysts do not attach to the apical plasma membrane of pinopode presenting cells. Trophoblast cells display contact with endometrial epithelial cells at the lateral plasma membranes by sharing apical junctional complexes. The function of endometrial pinopodes during human blastocyst implantation still remains to be elucidated. Ultrastructural studies indicate that the pinopode presenting apical plasma membrane does not participate directly in embryo-endometrial interactions.

In vitro models of human blastocyst implantation.

This paper reviews different in vitro models used for the study of blastocyst implantation in animals and the human. Furthermore, results from human blastocyst-endometrial interactions in vitro, investigated by scanning electron microscopy (SEM), light microscopy (LM) and transmission electron microscopy (TEM), are presented. SEM demonstrates the preference of human blastocysts to adhere to pinopode-presenting areas on endometrial cell cultures. LM and TEM show that the first morphological sign of cell contact, defined as junction formation, is present at the apical-to-lateral border of endometrial epithelial cells, whereas trophoblast attachment to apical endometrial epithelial plasma membranes was not observed. More advanced stages illustrate that the human blastocyst penetrates the epithelial lining by the intrusive penetration mechanism.

Ultrastructure of endometrial epithelial cells in a three-dimensional cell culture system for human implantation studies.

PURPOSE: A three-dimensional cell culture system imitating normal uterine endometrium has previously been established. To what degree do cultured epithelial cells retain their morphological characteristics as compared to in vivo material obtained simultaneously from the same tissue donor. RESULTS: We found a high degree of similarity between the in vivo and in vitro situations. The present culture system furthermore imitates the day-to-day morphology of the cycle. CONCLUSIONS: This indicates, that a correct timing of the biopsy tissue is important for future human implantation studies.

Ultrastructure of human blastocyst-endometrial interactions in vitro.

The interactions of seven human blastocysts with cultured endometrial cells were investigated by light microscopy and transmission electron microscopy. Trophoblastic-endometrial contact was observed at the lateral border of endometrial epithelial cells where trophoblast and endometrial epithelial cells shared apical junctional complexes and desmosomes. The first sign of penetration was invasion of a trophoblastic cytoplasmic protrusion between endometrial epithelial cells. In broad contact areas, lateral displacement of endometrial epithelial cells and formation of a peripheral pseudostratified epithelium were observed. When trophoblastic cells were interposed fully among endometrial epithelial cells, they formed a penetration cone and appeared to dislodge endometrial epithelial cells from the stromal compartment. A single penetration cone only was found in each specimen. Endometrial or trophoblastic degeneration was not observed. Formation of multinucleate (>/= three nuclei per cell) trophoblast cells was not observed, but many cells displayed areas with abrupt disappearance of well-defined plasma membranes, which is indicative of syncytium formation. In this study, adhesion and penetration occurred at the same time. The human blastocysts penetrated the endometrial surface epithelium by intrusive penetration. Epithelial penetration was achieved primarily by cellular syncytiotrophoblast-like cells and the first indications of syncytium formation were observed simultaneously with penetration of the epithelium.

Isolation and culture of human endometrial cells in a three-dimensional culture system.

A cell culture system was established in which endometrial stromal cells were embedded in a collagen matrix and separated from the endometrial epithelium by basement membrane material (Matrigel). The epithelium, seeded on top of the collagen matrix, grew in a monolayer. The cultures were evaluated by light microscopy and transmission and scanning electron microscopy. Light and transmission electron microscopy indicated a polarized columnar epithelium in monolayer with basally positioned nuclei. Scanning electron microscopy revealed a confluent epithelium with an abundance of microvilli and cilia, as well as pinopodes on the apical surface. Immunohistochemical staining for cytokeratin confirmed the epithelial origin of the surface cells, and staining for human collagen IV demonstrated its presence underneath the epithelial cells. This culture system represents a three-dimensional system that imitates the normal endometrium.

Presence of uterine pinopodes at the embryo-endometrial interface during human implantation in vitro.

In order to study changes occurring on the surfaces of human endometrial epithelial cells in the presence of an implanted blastocyst, we used scanning electron microscopy for investigation of five endometrial biopsies and three human implantation sites obtained in vitro. All specimens showed areas with endometrial pinopodes, separated by cells displaying microvilli or cilia at the apical surface. Pinopode formation was more pronounced in endometrial biopsies than in cell cultures. All blastocysts adhered to pinopode presenting cells. Endometrial surface changes were not seen around the blastocysts. The results of this study demonstrate that cultured endometrial epithelial cells are capable of pinopode formation. Furthermore, endometrial epithelial pinopodes, generally considered as a marker of endometrial receptivity, seem to be directly involved in the adhesion of the blastocyst to the endometrial surface.

Hydrosalpinx fluid does not adversely affect the normal development of human embryos and implantation in vitro.

Several retrospectively designed studies have shown an association between the presence of hydrosalpinx and impaired implantation and pregnancy rates among in-vitro fertilization (IVF) patients. In the present study we have evaluated the influence of hydrosalpinx fluid on normal human embryo development and implantation. Surplus, donated frozen embryos (n = 183) from IVF patients were used to study the effects on blastocyst development of hydrosalpinx fluid at concentrations of 50 and 100% compared with controls in S2 medium. The fluids were analysed for concentrations of electrolytes, osmolarity, protein content, endotoxin levels, bacterial or fungal contamination, pH and haemoglobin content. There was no difference in blastocyst development in cultures under mineral oil when control cultures (15/42 = 36%) were compared with cultures in 50% hydrosalpinx fluid (32/96 = 33%). The only biochemical parameter which correlated with capacity for blastocyst development was pH in hydrosalpinx fluid/medium (50/50%) after equilibration in 5% CO2 in air. When embryos were cultured in 100% hydrosalpinx fluid the blastocyst development was 14% (5/36) in comparison to control 33% (3/9). The original experiment was repeated in an open culture system without the protection of mineral oil but still in the presence of 50% hydrosalpinx fluid. The rate of blastocyst development was within the same range in the open system. In three separate experiments, the capability of expanded blastocyst to implant on multilayer artificial endometrium was tested. In these experiments, 1/3, 4/5 and 9/9 blastocysts implanted. The present study demonstrates that hydrosalpinx fluid does not generally exert any major negative effects on in-vitro development of human embryos or on the implantation process in vitro.