Search Results (139)

Pig somatic cell nuclear transfer (SCNT) has valuable applications in agriculture, biomedicine, and life sciences, yet low cloning efficiency remains a major constraint limiting its application. To systematically investigate factors related to the production efficiency of pig cloning, this study conducted a retrospective analysis of 367,701 SCNT embryos transferred into 2019 surrogate sows over five years, focusing on breeds of donor cells, the season of embryo transfers, and the number of embryos transferred per surrogate. Our data demonstrate that the genetic background of donor cells is a critical determinant. SCNT embryos generated by wild-type (WT) Pietrain and Duroc pigs yielded significantly higher cloning efficiencies compared to those from Large White and Yorkshire pigs. This breed-specific influence was also observed with genetically modified (GM) donor cells. Nevertheless, within the GM groups, GM-Duroc and GM-Yorkshire showed superior efficiency compared to GM-Large White and GM-Bama. Furthermore, Summer was identified as the least favorable season for embryo transfer, with significantly lower pregnancy rates, delivery rates, and cloning efficiency compared to the other seasons. Importantly, we established that transferring 100–150 embryos per recipient optimized cloning efficiency, significantly outperforming groups receiving higher embryo numbers without compromising pregnancy rates, delivery rates, or average litter sizes. Our findings provide valuable guidance for optimizing large-scale SCNT protocols in swine. Full article

Background/Objectives: Uterine fibroids are the most common benign neoplasms of the female genital tract, with a prevalence of 20% to 40% among women of reproductive age. Their management in the context of Assisted Reproductive Technologies (ART) represents a major clinical challenge, characterized by controversies, contrasting approaches, and a lack of shared guidelines. Indeed, the detrimental effects of fibroid treatments are not well known and may be influenced by the size, location, and number of fibroids. The impact of hysteroscopic myomectomy in women affected by submucosal myomas (FIGO classification type: G0–G2) is well documented in the current literature; however, the impact of intramural and subserosal myoma removal (FIGO types 3–8), in particular those <4/5 cm in diameter, remains controversial. The aim of the present study is to introduce and share a pragmatic surgical approach to uterine fibroid management prior to In Vitro Fertilization (IVF), to reduce the knowledge gap regarding uterine fibroid treatment. Methods: We conducted a retrospective observationally study that included 94 cases of infertile women, who underwent myomectomy at our IVF centre at Sandro Pertini Hospital, Rome, Italy, between 2020 and 2025. These patients met the inclusion criterion of having an idiopathic/tubal factor of infertility and were aged < 40. We evaluated a group of 17 women (group A) who underwent hysteroscopic myomectomy for submucosal fibroids (FIGO types 0–2) and a group of 39 women (group B) who underwent open (laparotomic) myomectomy for intramural/subserosal fibroids (FIGO types 3–8). Group B was compared with a control group of 38 women who were similar in terms of all demographic and clinical parameters and myoma features (group C) and did not want to undergo a myomectomy procedure. All surgical procedures were executed by the same expert surgeon following our proposed model: submucosal fibroids were always removed by operative hysteroscopy, while intramural/subserosal fibroids were removed if there were three or more and if they were at least 1 ≥ 3 cm in size. All enrolled patients subsequently underwent IVF treatment at our centre, which consisted of an antagonist protocol for ovarian stimulation, and all transferred embryos were of good quality according to the recent European Society of Human Reproduction and Embryology (ESHRE) classification. Results: In group A, we observed an implantation rate of 41% and a clinical pregnancy rate of 35.2%, and these results are consistent with the current literature. In group B, we obtained statistically significant differences in the implantation (31% vs. 12.9%) and pregnancy rates (28.1% vs. 7.8%) compared to group C (p = 0.02 and p = 0.03, respectively). In addition, the live birth rate was statistically higher compared to that in group C (p < 0.01). Miscarriage and preterm delivery rates were lower in group B, although the differences were not statistically significant. No severe post-surgical complications, such as uterine rupture, were observed during subsequent pregnancies. Conclusions: Despite the limited patient sample size, the monocentric experience, and the retrospective design, we emphasize the effectiveness of our proposed surgical model in women affected by myomas. Indeed, the surgical treatment of submucosal, intramural, and subserosal lesions may improve ART and pregnancy outcomes (through a higher implantation rate, pregnancy rate, and live birth rate, as well as a lower miscarriage/preterm rate). Full article

Background and Objectives: To evaluate the impact of gonadotropin-releasing hormone agonist (GnRHa) triggering compared to human chorionic gonadotropin (hCG) triggering on frozen–thawed and fresh embryo transfer outcomes in patients with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization (IVF). Materials and Methods: This retrospective cohort study analyzed 267 IVF cycles of 261 PCOS patients treated with GnRH antagonist protocols. Patients were divided into three groups: GnRHa-triggered frozen–thawed embryo transfer (ET) (n = 126), hCG-triggered frozen–thawed ET (n = 68), and hCG-triggered fresh ET (n = 73). Baseline characteristics, stimulation parameters, and cycle outcomes were compared between groups. A binary logistic regression analysis was established to identify independent predictors of clinical pregnancy. Results: The GnRHa-triggered group had significantly higher numbers of retrieved oocytes, mature (MII) oocytes, and fertilized oocytes compared to both hCG-triggered groups (p < 0.001). The number of obtained embryos and frozen embryos (good-quality embryos) was highest in the GnRHa group (p < 0.001). However, clinical pregnancy rates were comparable between the groups with a similar number and grade of transferred embryos (32.53%, 38.23%, and 32.87%, respectively). Multivariate regression analysis revealed that the grade of the transferred embryo was a significant predictor of clinical pregnancy (p = 0.034). Conclusions: This study provides insights into different triggering strategies for final oocyte maturation in PCOS patients. GnRH-agonist-triggered frozen–thawed cycles showed comparable clinical pregnancy outcomes to those of hCG-triggered cycles, with a potentially lower OHSS risk. The findings suggest that individualized triggering approaches based on patient characteristics and OHSS risk may be beneficial for PCOS patients undergoing IVF. Full article

Background: Infertility is a multifactorial condition that causes significant emotional distress and financial burden for couples. Despite advances in assisted reproductive technologies (ARTs), many patients experience recurrent implantation failure (RIF) or pregnancy loss. Intralipid, an intravenous lipid emulsion, has been proposed as an adjunctive therapy due to its immune-modulatory effects, particularly in reducing elevated natural killer (NK) cell activity, which may be associated with poor reproductive outcomes. This study evaluated the effect of intralipid infusion on pregnancy rates and miscarriage rates in women with recurrent implantation failure undergoing in vitro fertilization (IVF). Materials and Methods: This was a retrospective study of women who had suffered from recurrent implantation failure and underwent IVF between September 2023 and September 2024. A comparative group undergoing IVF but who did not have recurrent implantation failure matched for age was selected. Outcomes of clinical pregnancy, miscarriage and livebirth rates were compared in both groups. Results: A total of 113 women undergoing IVF were identified and 51 received intralipid. Intralipid was initiated at varying stages of the IVF process, a day before embryo transfer (ET) (18 or 35.3%), on the day of ET (20 or 39.2%) and after ET (13 or 25.5%). The clinical pregnancy rate was 44.2% in the treatment group compared to 29% in the comparator group (p < 0.05) while the miscarriage rates were 13.7% versus 11.3% (p > 0.05). Elevated NK cells were present in 65.4% of the patients who received intralipid, but the correlation between NK cell levels and pregnancy outcomes was weak (Spearman ρ = 0.032). No adverse effects were reported in any of the women. Conclusions: Intralipid infusion increased the successful pregnancy rates in women who had recurrent implantation failure during IVF. The successful pregnancy rate was significantly higher than that in those undergoing ART who had not suffered from RIF. These findings support several studies on the potential benefit and safety of intralipids in women undergoing ART, but the numbers remain small and more prospective studies are needed to confirm these findings Full article

Aim: This study aimed to compare the clinical pregnancy outcomes of Day 3 (cleavage-stage) and Day 5 (blastocyst) frozen–thawed embryo transfers in assisted reproductive technology (ART) cycles. Methods: A retrospective analysis was conducted on 6455 patients who underwent frozen–thawed embryo transfer (FET) between 1 April 2010 and 1 April 2023, at SBÜ Etlik Zübeyde Hanım Women’s Health Training and Research Hospital. Patients were categorized based on embryo transfer type, and clinical outcomes were compared using statistical analyses. Results: Pregnancy rates were significantly higher in the blastocyst transfer group (p = 0.031). The cleavage-stage group had a higher number of embryo transfers (p < 0.001), likely due to lower implantation potential per embryo. Patients with diminished ovarian reserve had lower embryo freezing rates (p < 0.001). Blastocyst-stage transfers showed better synchronization with endometrial receptivity but carried a risk of embryo attrition. Conclusions: Blastocyst transfer is associated with higher pregnancy rates and should be preferred when viable embryos are available. However, cleavage-stage transfer remains an alternative for patients with poor embryo development. An individualized approach is essential for optimizing ART outcomes. Full article

Repeat breeder (RB) cows are subfertile animals and represent a major issue in the livestock industry. The influence of the gut microbiota on reproductive function and the gut microbiota–gonadal axis has garnered scientific attention. This study aimed to evaluate the relationship between reproductive performance and gut microbiota in Holstein cows, depending on reproductive attempts (number of artificial inseminations or embryo transfers) and subsequent pregnancy outcomes. Fecal samples were collected from Holstein cows at the time of ovulation and classified into four groups: Normal pregnancy (n = 27, ≤three reproductive attempts, subsequently fertile), Normal open (n = 25, ≤three reproductive attempts, subsequently infertile), RB pregnancy (n = 38, over four reproductive attempts, subsequently fertile), and RB open (n = 60, over four reproductive attempts, subsequently infertile). The PLS-DA analysis revealed differences in classification among groups, especially between Normal pregnancy and RB open. Regarding α- and β-diversity analyses, these indices were significantly different among the four groups (p < 0.05). Using LEfSe analysis, three genus-level bacteria (Bacillus, Ruminococcus, and Sphingobium) were identified as specific bacteria in the Normal pregnancy group, and eight genus-level bacteria (Huintestinicola, Intestinimonas, Neglecta, Oscillibacter, Zongyangia, Phocaeicola, Alistipes, and Acholeplasma) were identified as specific bacteria in both open groups (p < 0.05). KEGG analysis predicted some pathways (Apoptosis, Lipopolysaccharide biosynthesis, etc.) to be enriched in both the open groups. MetaCyc analysis predicted amine and polyamine degradation/biosynthesis as the specific changing pathways in the RB open group. This study demonstrated that the composition of the gut microbiota differs between normal fertility and repeated infertility conditions. Furthermore, even with fewer reproductive attempts, differences in gut microbiota composition were observed between cows that conceived and those that failed to conceive. Full article

The aim of our study was to provide a retrospective single-center experience of the additional workload associated with routine PGT, including embryologist training and suggested staffing levels. A total of 4945 IVF cycles were retrospectively considered, of which 1680 were PGT cycles with a total of 5258 biopsied blastocysts. An exponential increase in the proportion of PGTs over OPUs was observed, from 0.2% in 2015 to 72.9% in 2024. The number of viable embryos for biopsy was significantly increased by the systematic adoption of an extended embryo culture and the concomitant transition from a day 2 Double Embryo Transfer (DET) to a day 5 Single Blastocyst Transfer (SET) policy in 2020. In order to cope with the increasing workload, a concomitant increase in the number of embryologists involved in blastocyst biopsy was adopted, with a second embryologist in 2020, a third in 2021, and a fourth in 2022, with a trend comparable to that observed for the proportion of PGT cycles over IVF cycles performed during the study period. The appropriate number of staff required for the IVF laboratory was calculated using the Staffing Model for ART (smART) calculator, based on 12 routine IVF procedures. An optimal balance between operational procedures and staffing levels was achieved when the difference (Δ) was ≤10%, ensuring the efficient maintenance of PGT in the IVF laboratory. Full article

Background/Objectives: The success of artificial reproductive technologies (ARTs) depends on different factors, such as patient-specific reproductive features, ovarian response to stimulation, oocyte and embryo quality, and endometrial receptivity. This study aimed to evaluate their association with oocyte yield, fertilization, endometrial thickness, and pregnancy outcomes. Methods: A prospective clinical study included 128 women undergoing IVF/ICSI. Baseline hormone levels (E2, P4, FSH, LH, AMH) were assessed prior to stimulation. E2 levels were monitored during stimulation, and P4 was measured on the day of oocyte retrieval. Patients were grouped based on P4 levels (<2 ng/mL vs. ≥2 ng/mL). IVF outcomes and endometrial characteristics were statistically analyzed. Results: Lower P4 levels (<2 ng/mL) on the day of oocyte retrieval were significantly associated with higher fertilization rates (p < 0.003), more fertilized oocytes (p < 0.001), and increased pregnancy rates (p < 0.001). Elevated P4 (≥2 ng/mL) correlated with a higher frequency of thin endometrium (<7 mm, p < 0.007). E2 levels on the hCG trigger day correlated positively with the number of retrieved and mature oocytes and fertilization outcomes (p < 0.05). Patients who achieved pregnancy had lower P4 and BMI, and higher E2, AMH, and endometrial thickness. ROC identified a P4 threshold of 1.99 ng/mL with moderate predictive value. Conclusions: Elevated progesterone levels on the day of oocyte retrieval negatively impact fertilization and pregnancy outcomes, likely due to impaired endometrial receptivity. Combined assessment of P4, E2, AMH, and endometrial thickness may enhance embryo transfer planning and improve IVF success rates. Full article

Zygotic genome activation (ZGA) represents one of the most vulnerable periods to environmental perturbations. The objective of this study was to investigate the formation of stress granules in mouse embryos in response to temperature reduction during ZGA, preimplantation embryo mortality, and long-term phenotypic outcomes. These outcomes included the evaluation of expression noise in bilateral right/left limbs of offspring as an indicator of developmental instability, behavioral deviation, hippocampal volume, and metabolomics profiling in adult offspring. Exposure to hypothermia during ZGA was associated with an increased number and inter-blastomere variability of stress granules, extended duration of the second embryonic division, and elevated embryonic mortality during the second and third cleavage stages. The embryonic response to hypothermic stress correlated with phenotypic traits indicative of increased pathology risk. Expression noise, serving as an indicator of developmental instability, was reduced in adult offspring derived from two-cell embryos incubated at 35 °C compared to those at 37 °C, while showing no significant difference relative to the control group. These results suggest that embryos surviving hypothermic exposure (35 °C) possess enhanced resilience to the adverse effects commonly associated with embryo transfer procedures. Furthermore, increased hippocampal volume and augmented auditory startle reflex observed in offspring that endured hypothermia during ZGA imply reduced risks of cognitive-related pathologies and reduced risks of pathologies associated with cognitive functions. Full article

Background/Objectives: GnRH agonists may offer potential benefits when used for luteal phase support in assisted reproductive treatments. This systematic review and meta-analysis of randomized controlled trials evaluates the effect of a single-dose administration of gonadotropin-releasing hormone (GnRH) agonist on the day of frozen-thawed embryo transfer (FET) in artificial cycles, in terms of reproductive outcomes. Methods: A comprehensive literature search was performed using the PubMed and Cochrane databases to identify relevant studies. The outcomes assessed were live birth rate, clinical pregnancy rate, positive pregnancy test, implantation rate, and miscarriage rate. Three randomized controlled trials were included in the analysis. Results: The clinical pregnancy rate (56.5% vs. 47.4%; OR 1.27; 95% CI: 1.01–1.60; p = 0.0426) and live birth rate (34.3% vs. 23.9%; OR 1.71; 95% CI: 1.00–2.91; p = 0.0483) were significantly higher in the treatment group compared to the control group. No statistically significant differences were observed between the groups in terms of positive pregnancy test, implantation rate, or miscarriage rate, although the analysis revealed a trend toward improved outcomes in the intervention group. Conclusions: In summary, although our meta-analysis indicates that a single dose of GnRH agonist in artificial FET cycles may be associated with improved clinical pregnancy and live birth rates, these findings are based on a limited number of available trials. Larger, well-designed randomized controlled trials are urgently needed before any changes to clinical recommendations can be justified. Full article

This study aimed to compare sperm parameters and reproductive outcomes after sperm selection using microfluidic chips versus conventional techniques (swim-up/density gradients). A systematic review and meta-analysis were performed after the extraction of relevant data from thirty-nine studies that met the inclusion criteria. Mean difference or odds ratio was calculated for each outcome. The analysis revealed that sperm selection using microfluidics yields lower sperm DNA fragmentation (MD = −9.98 [−13.19, −6.76], p < 0.00001), increased progressive motility (MD = 14.50 [7.84, 21.71], p = 0.04), total motility (MD = 10.68 [6.04, 15.31], p < 0.00001) and morphology (MD = 1.41 [0.67, 2.16], p = 0.0002). Significant differences were also found in the fertilization rate/MII oocyte microinjected (OR = 1.22 [1.01, 1.46], p = 0.04), implantation rate/embryo transfer (ET) (OR = 4.51 [1.42, 14.37], p = 0.01), clinical pregnancy/ET (OR = 1.73 [1.22, 2.45], p = 0.002), ongoing pregnancy/ET (OR = 1.99 [1.03, 3.83], p = 0.04), live birth rate/first cycle (OR = 1.59 [1.12, 2.24], p = 0.009) and per all embryo transfer (OR = 1.65 [1.06, 2.55], p = 0.03). No significant differences were found in embryo euploidy/number of biopsied blastocysts (OR = 1.34 [0.88, 2.04], p = 0.77), biochemical pregnancy/ET (OR = 1.23 [0.84, 1.80], p = 0.29), miscarriage rate/cycle (OR = 0.84 [0.54, 1.31], p = 0.35) and per pregnancy (OR = 0.71 [0.50, 1.02], p = 0.07), live birth rate/first embryo transfer (OR = 1.60 [0.80, 3.22], p = 0.18) and per concluded cycle (OR = 1.03 [0.53, 2.00], p = 0.92). To summarize, microfluidics may offer a beneficial approach in certain situations, particularly for patients with elevated sperm DNA fragmentation (SDF) levels. However, its integration into routine clinical practice cannot be justified yet in terms of cost-effectiveness. Additional research is needed to provide more comprehensive data on reproductive outcomes, especially live birth rates, which remain the ultimate goal of assisted reproductive technologies. Full article

Objective: Most studies concentrate on comparisons between the cleavage stage and blastocyst stage of embryos during in vitro stimulation treatment. We aimed, in this study, to compare the pregnancy rates of day 4 or day 5 blastocyst transfers, all derived from fresh, antagonist-regulated in vitro fertilization (IVF) cycles, and to evaluate the factors affecting pregnancy success. Methods: This retrospective cohort study evaluated 3681 fresh embryo transfer cycles conducted at a private IVF center between 2019 and 2021. Patients were divided into two groups based on the day of embryo transfer: day 4 (Group 1) and day 5 (Group 2). Subgroup analyses were performed according to age (≤40 vs. >40 years) and the number of oocytes retrieved (≤4 vs. >4). All patients underwent ovarian stimulation with FSH alone or in combination with hMG, and GnRH antagonist protocols were used for pituitary suppression. Final oocyte maturation was triggered with recombinant hCG, and fertilization was achieved via intracytoplasmic sperm injection (ICSI) for all cases. Embryos were cultured in sequential media and assessed daily until transfer on day 4 or day 5, based on embryo morphology and clinic logistics. Results: Pregnancy was more likely among women under 40 than among women over 40. There were a total of 1217 women who underwent day 4 transfer and 2464 women who underwent day 5 transfer. A total of 660 (54.2%) of the women transferred on day 4 developed pregnancy. Among those transferred on day 5, 1610 (65.3%) developed pregnancy. When compared to the 4th day, a single embryo transfer on the 5th day enhances pregnancy success by 1.8 times, while two embryo transfers raise it by 1.6 times. Furthermore, when the number of oocytes is greater than four and the number of embryos transferred is two, the pregnancy success rate is 2.5 times higher when embryo transfer is performed on the fifth day versus the fourth day. Regardless of age, oocyte count, or number of embryos transferred, 5th-day fresh embryo transfers enhanced pregnancy success by 1.9 times compared to 4th-day transfer. Conclusions: Transfers of fresh embryos on day 5 are superior to those on day 4 and should be favored, especially for people over the age of 40, regardless of the number of embryos transferred, even if that individual has fewer than four oocytes. Full article

Background/Objectives: Preimplantation genetic screening improves embryo selection in intracytoplasmic sperm injection cycles, especially for women of advanced maternal age. As chromosomal normality declines with age, high-dose gonadotropins are commonly used to enhance follicular response. This study compares minimal and high-dose stimulation protocols in terms of euploidy, pregnancy, and live birth rates following single embryo transfer. Methods: In this prospective study, 198 women aged 38–45 years were enrolled and divided into two groups: minimal stimulation (100 mg clomiphene citrate and 75 IU human menopausal gonadotropin) and high stimulation (300–450 IU gonadotropins). Women with severe male factor infertility, endometriosis, or absolute tubal factor were excluded. Clinical outcomes were compared using a t-test or Mann–Whitney U test. Results: Baseline characteristics were similar between groups. The high-dose group had a significantly higher number of retrieved oocytes (p = 0.009) and metaphase II oocytes (p = 0.003). However, there were no significant differences in euploid embryo rates (35.4% vs. 37.4%, p = 0.768), clinical pregnancy rates (67.6% vs. 69.4%, p > 0.999), gestational sac rates (58.8% vs. 58.3%, p > 0.999), or live birth rates (47.1% vs. 50.0%, p = 0.995). Conclusions: This is the first prospective study to compare euploid embryo rates, pregnancy rates, and live birth rates between minimal stimulation protocol and high stimulation protocol in AMA patients. Although there has been no difference in euploid and pregnancy rates, minimal stimulation protocol has advantages in cost and comfort. Full article

Infectious bursal disease (IBD) is a viral disease that most commonly affects young chickens and destroys lymphocytes, leading to immunosuppression. The field study aimed to investigate the effect of three different vaccines administered in ovo against IBD and spray against Newcastle disease (ND) on serological response tested for IBD and ND and histopathological analysis of the bursa of Fabricius (BF) and quantitative B lymphocytes in BF in broiler chickens. The study was conducted on a farm of four hen houses with 30,000 chicks in each building. Three different vaccination programs were used in the poultry hatchery, and one hen house IV was not vaccinated. All three groups were vaccinated at 18 days and 9 h in ovo during egg transfer against IBD at a dose of 0.05 mL/embryo, group I vector vaccine (strain vHVT013-69), group II immunocomplex vaccine (strain Winterfield 2512), group III immunocomplex vaccine (strain M.B, 0.05). Then, after hatching, the chicks were vaccinated in a spray (groups I, II, and III) against NDV (strain VG/GA, 20 mL/100 birds) and infectious bronchitis (IBV) in a spray (strain H-120, serotype Mass, and strain CR88121, serotype 793B) at a dose of 20 mL/100 chicks. On days 1, 21, 31, and 41, blood was collected for serological tests to determine the antibody titer against IBD, which was performed using two tests (IDEXX and ID-Vet) and against ND. During the necropsy of birds on days 21 and 31, the bursae of Fabricius were collected from five chickens for histopathological evaluation of BF and quantitative B lymphocyte counts; a total of 40 bursae were analyzed (10 per group). The vaccination program applied significantly (p < 0.05) affected the immune response expressed as a geometric mean titer (GMT) in the serum of the examined chickens against IBDV on days 21, 31, and 41. Differences were also demonstrated in the mass and level of BF damage and the number of B lymphocytes. No significant differences were demonstrated in the GMT in the serum of the examined chickens against NDV depending on the vaccination program applied. Full article

Background and Objectives: The aim of this study is to evaluate the relationship between serum estradiol (E2) levels measured on the day of antagonist administration and live birth rates (LBRs) in women undergoing IVF-ET with an antagonist protocol. Materials and Methods: Data from women who underwent IVF-ET with an antagonist protocol between 2011 and 2023 were retrospectively analyzed. Patients were divided into five groups on the basis of serum E2 levels measured on the day of antagonist administration (Group I: E2 < 400 pg/mL, Group II: 400 ≤ E2 < 650 pg/mL, Group III: 650 ≤ E2 < 800 pg/mL, Group IV:800 ≤ E2 < 1000 pg/mL, and Group V: E2 ≥ 1000 pg/mL). The independent effect of serum E2 levels on live birth was analyzed via an adjusted regression model. Results: A total of 1613 patients were included in the study. The overall LBR was 32.1%. The LBRs for Groups I, II, III, IV, and V were 28.9%, 37.8%, 26.4%, 32.2%, and 34.1%, respectively (p = 0.017). In the adjusted regression model, serum E2 levels measured on the day of antagonist administration < 400 pg/mL (OR: 0.752, 95% CI: 0.580–0.999, p = 0.048) and 650 ≤ E2 < 800 pg/mL (OR: 0.595, 95% CI: 0.388–0.911, p = 0.011) were identified as factors that reduce the likelihood of a live birth, adjusting for age, infertility duration, body mass index (BMI), cycle number, quality of embryo, and number of embryos transferred. Conclusions: The serum E2 level associated with the highest LBR in women undergoing IVF-ET with an antagonist protocol was found to be in the range of 400–650. Serum E2 levels < 400 pg/mL or in the range of 650–800 pg/mL were statistically significantly associated with a reduced LBR. Full article