Introduction: Compaction is the first event in embryo morphogenesis. Blastocyst transfer on day five or six has been widely performed in the last decade. We investigated the clinical value of early compaction on day three for evaluation of the transferred embryo quality and pregnancy. Methods: Four hundred patients with female factor infertility and 776 fresh embryo transfers were included. Two groups were formed: Early compaction group had embryo transfer with at least one day-three embryo exhibiting early compaction. Transferred embryos without early compaction comprised the control group. Embryo transfer was performed on day three or five after the assessment of embryo compaction by a time-lapse technology system. Each patient underwent only a single cycle of embryo transfer. We analyzed fertilization, pregnancy, and live birth rates. Results: We detected significantly higher numbers of the retrieved oocytes, metaphase II (MII) oocytes, and fertilized oocytes in the early compaction group. Moreover, the transfer of the early compacting embryos on day three resulted in higher pregnancy and live birth rates. Conclusion: Our data suggest that early compaction might be a factor to determine good quality embryos and embryo transfer day.

Non‑invasive fluid biopsies are emerging as a promising, low‑risk complementary method to traditional diagnostic approaches in reproductive biology, allowing for repeated sampling throughout different stages of assisted reproductive technology. These approaches hold significant potential, not only for clinical diagnosis, but also for personalized medicine. The present review summarizes recent findings on key biomolecular components found in accessible body fluids, such as follicular fluid, embryo culture medium, uterine secretions and saliva, namely cell‑free nucleic acids, extracellular vesicles and microRNAs. These biomarkers indicate critical cellular events, such as apoptosis, oxidative stress, mitochondrial dysfunction and intercellular signaling pathways. Special emphasis is placed on the molecular profile of granulosa and cumulus cells, which are essential for oocyte maturation and have strong predictive value for fertilization potential and subsequent pregnancy outcomes. Their molecular signatures provide critical information about the developmental competence of the oocyte and early embryo. However, limitations such as maternal contamination, mosaicism and variable compliance, along with a lack of guideline‑level approval, currently restrict their routine clinical use. These non‑invasive samples are valuable complements to current invasive methods, providing information about chromosomal competence and embryo viability without compromising embryo integrity. Overall, the current evidence highlights the potential of fluid‑based biomarker discovery to improve the outcomes of in vitro fertilization (IVF) and support the development of personalized, sustainable fertility treatments. The present review aimed to summarize and critically evaluate developments in non‑invasive liquid biopsy techniques in IVF, highlight their clinical applications for improving IVF outcomes, and examine the molecular profile of granulosa and cumulus cells as determinants of oocyte and embryo quality. The fundamental hypothesis is that non‑invasive liquid biopsies can serve as effective, low‑risk alternatives to traditional invasive diagnostic approaches, minimizing harm to patients and embryos, while improving embryo selection, preimplantation genetic testing and overall IVF success.

Background: Diminished ovarian reserve is characterized by a decrease in oocyte count and estrogen levels, which leads to infertility. The genetic and epigenetic mechanisms in MI to MII transition or complete MII phase in the oocyte maturation process estrogen receptor alpha and piRNA relationship were evaluated. Methods: This study analyzed 100 cumulus oophorous complex samples from normoresponder and DOR patients undergoing IVF, subdivided into metaphase I and metaphase II stages. To elucidate the ER-α, PIWIL3, piR-651, and piR-823 genes qRT-PCR was used and qualitative ER-α protein expressions were determined by immunohistochemistry. Pearson’s correlation analysis was utilized to evaluate the interactions between genes within each experimental group. Results: The DOR samples exhibited significant downregulation of ER-α gene and protein expression compared to the NOR controls. PIWIL3 gene, piR-651, and piR-823 expressions reduced in DOR MI and MII. Strong positive correlations among ER-α, PIWIL3, piR-651, and piR-823 were observed in NOR, whereas DOR showed weaker correlations and immunohistochemistry verified lower ER-α protein levels in DOR. Conclusions: The disruption of ER-α and piRNA-related gene networks in DOR may underlie the suboptimal maturation of oocytes, and monitoring ER-α, PIWIL3, piR-651, and piR-823 expressions could facilitate early determination of maturation stages and improve assessment of ovarian reserve. The potential for transposition to MII in NOR and DOR oocytes was observed in relation to the association between ER-α protein/gene expression and PIWIL3, which regulates ER-α. Moreover, piR-651 and piR-823, whose expressions depend on estrogen level, indirectly regulate oocyte maturation from MI to MII in both NOR and DOR epigenetically. We suggest that the MI and MII stages of oocytes could be determined earlier in NOR and DOR cases by controlling ER-α, PIWIL3, piR-651 and piR-823 expressions. These molecular markers indicate promise for diagnostic applications in reproductive medicine, warranting further validation in larger cohorts.

An embryo culture medium is a specialized set of ambient conditions, technological equipment, and nutrients that embryos require to grow properly. We aimed to investigate the Ki-67, hTERT, and HIF-1α gene expression differences between developing and non-developing embryos in spent embryo culture medium. Ki-67, hTERT, and HIF-1α gene expressions were determined from the spent embryo culture medium containing developing and non-developing embryos of 20 normoresponder patients admitted to the Bahçeci Umut IVF Center. An increase in hTERT gene expression (p < 0.05) and a decrease in HIF-1α gene expression (p < 0.001) were observed in mediums of developing compared to the non-developing embryos. No difference was observed in Ki-67 gene expression (p > 0.05). While there was a correlation between Ki-67 and HIF-1α genes in the non-growing group (r < 0.01); no correlation was observed in the developing group (r > 0.05). Both normoresponder groups will be similar in terms of proliferation rate. The low HIF-1α expression that observed high telomerase activity in embryo development maintains continuity and avoids mechanisms that result in cell death. A molecular study of the embryo development in patients with similar characteristics may help to understand the pathogenesis of the disease and establish a diagnosis and specific treatment.