External bending of cryodevice during vitrification leads to cryoprotectant cracks and damage to embryo blastomeres.

RESEARCH QUESTION: Embryo blastomeres and the zona pellucida are occasionally damaged during vitrification; is this a result of crack-induced mechanical damage in the glass state, caused by external bending of the device? DESIGN: A stereomicroscope was used to observe external bending-induced cracks in a cryoprotectant. Thereafter, 309 human cleavage-stage embryos derived from abnormally fertilized eggs were used to assess embryo damage under two external bending conditions: forward bending and backward bending, with three bending degrees applied. Three distinct embryo positions were used to examine the correlation between bending and embryo damage. Damage was assessed by looking at blastomere lysis rates, and overall rates of damaged and surviving embryos. RESULTS: A series of parallel cracks were identified in the cryoprotectant used for external bending, which led to damage to the embryo blastomeres. Compared with forward bending and control, the embryos were found to be more easily damaged by backward bending, indicated by significantly higher blastomere lysis and embryo damage rates, and lower embryo survival rate of backward bending than forward bending (P < 0.001). The degree of embryo damage also increased as the degree of external forces increased. Embryo position correlated with degree of embryo damage. CONCLUSIONS: Cryoprotectant crack-induced damage was identified as the cause of embryo damage. Mechanical damage to the glass state occurs because of improper external bending of the cryodevice strip in liquid nitrogen during vitrification. To prevent damage, bending of the strip should be avoided and the embryos should be placed near the tip of the strip.

The press-assisted fusion scheme significantly mitigates the quantity of HVJ-E required in mitochondrial replacement techniques.

In brief: The impact of HVJ-E employed in mitochondrial replacement techniques (MRTs) on embryonic development remains uncertain. This study has exhibited the influence of HVJ-E utilized in MRTs on embryonic development and has devised a novel HVJ-E-induced fusion approach to curtail the amount of HVJ-E employed in MRTs. Abstract: Mitochondrial replacement techniques (MRTs) provide a viable option for women carrying pathogenic mitochondrial DNA (mtDNA) variants to conceive disease-free offspring with a genetic connection. In comparison to electrofusion, HVJ-E-induced fusion has been identified as the most promising approach for clinical translation of MRTs due to its absence of electrical interference. However, despite confirmation of the absence of RNA activity in HVJ-E, a reduction in blastocyst quality has been observed in various MRTs studies utilizing the HVJ-E-induced fusion scheme. Recent investigations have revealed a dose-dependent elevation of reactive oxygen species (ROS) levels in various cancer cells incubated with HVJ-E. However, the impact of HVJ-E as a sole determinant on embryonic development in MRTs remains unverified. This investigation establishes that the augmented concentration of HVJ-E utilized in the conventional HVJ-E fusion protocol is an autonomous variable that influences embryonic development in MRTs. This effect may be attributed to amplified DNA damage resulting from heightened levels of ROS in reconstructed embryos. To mitigate the presence of HVJ-E in reconstructed zygotes while maintaining optimal fusion efficiency in MRTs, a novel HVJ-E-induced fusion approach was devised, namely, press-assisted fusion. This technique offers potential advantages in reducing detrimental factors that impede embryo development in MRTs.

Neonatal outcomes and congenital malformations in children born after progestin-primed ovarian stimulation protocol.

Purpose: The purpose of this study is to assess the safety of progestin-primed ovarian stimulation (PPOS) protocol regarding the neonatal outcomes and congenital malformations in babies born after in vitro fertilization (IVF) and frozen embryo transfer (FET). Methods: In this large retrospective cohort study, a total of 16,493 infants born between 1 September 2013 and 31 July 2021 from IVF and FET cycles after treatment with either PPOS (n = 15,245) or gonadotropin-releasing hormone antagonist (GnRH-ant) (n = 1,248) were finally enrolled. The primary outcome measure was the incidence of congenital malformations. The secondary outcome measures were rates of low birth weight (LBW), very low birth weight (VLBW), preterm birth (PTB), very preterm birth (VPTB), and early neonatal death. Results: Birth characteristics for both singletons and twins regarding the sex of infants, gestational age, birth weight, and birth length were comparable between the PPOS group and the GnRH-ant group. Rates of LBW, VLBW, PTB, VPTB, and early neonatal death were also similar. The reanalysis using propensity score matching (PSM) and multivariable logistic regression indicated that the PPOS protocol could not increase the risk of adverse neonatal outcomes compared with the GnRH-ant protocol. Furthermore, no significant difference was observed in the overall incidence of congenital malformations in live-born babies. After PSM and controlling for all confounders, the results remained insignificant with an adjusted odds ratio of 0.66 [95% confidence interval (CI) 0.32-1.34] and 2.43 [95% CI 0.97-6.06], respectively, for singletons and twins. Conclusions: Our study suggests that compared with GnRH-ant treatment for IVF, the PPOS protocol could not produce a negative effect on the newborn population in terms of neonatal outcomes and congenital malformations.

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

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

Frozen Embryo Transfer in Mildly Stimulated Cycle With Letrozole Compared to Natural Cycle in Ovulatory Women: A Large Retrospective Study.

Objective: To evaluate the clinical effect of mild stimulation with letrozole on pregnancy outcomes in ovulatory women undergoing frozen embryo transfer (FET) compared to natural cycle. Design: Retrospective observational study. Setting: Tertiary care academic medical center. Population: A total of 6,874 infertile women with regular menstrual cycles (21-35 days) met the criteria for this study in the period from 2013 to 2020. Methods: All patients who were prepared for and underwent FET were divided into two groups: a modified natural cycle (NC) group (n=3,958) and a letrozole cycle group (n=2,916). Main Outcome Measures: The primary outcome of the study was clinical pregnancy rate. Secondary outcome measures were endometrial thickness, rates of implantation, positive HCG test, live birth, early miscarriage and ectopic pregnancy. Results: The clinical pregnancy rate was not statistically different between the modified NC-FET group and the letrozole-FFT group before (crude OR 0.99, 95% CI 0.90-1.09, P=0.902>0.05) and after propensity score matching (PSM) (crude OR 1.01, 95% CI 0.91-1.12, P=0.870>0.05). After multivariable logistic regression analysis, the clinical pregnancy rate remained insignificant before (adjusted OR 1.00, 95% CI 0.91-1.10, P=0.979>0.05) and after matching (adjusted OR 1.00, 95% CI 0.89-1.11, P=0.936>0.05), respectively. Similarly, in the crude and adjusted analysis, the positive HCG test, implantation, live birth and early miscarriage rates were also comparable in the letrozole-FFT group and modified NC-FET group before and after matching. Furthermore, the endometrial thickness of letrozole-FFT group was similar to that of modified NC-FET group with adjusted analysis. Conclusion: Our observation suggests that mild stimulation with letrozole could produce similar pregnancy outcomes in ovulatory patients who undergo FET when compared with a natural cycle.

IDDB: a comprehensive resource featuring genes, variants and characteristics associated with infertility.

Infertility is a complex multifactorial disease that affects up to 10% of couples across the world. However, many mechanisms of infertility remain unclear due to the lack of studies based on systematic knowledge, leading to ineffective treatment and/or transmission of genetic defects to offspring. Here, we developed an infertility disease database to provide a comprehensive resource featuring various factors involved in infertility. Features in the current IDDB version were manually curated as follows: (i) a total of 307 infertility-associated genes in human and 1348 genes associated with reproductive disorder in 9 model organisms; (ii) a total of 202 chromosomal abnormalities leading to human infertility, including aneuploidies and structural variants; and (iii) a total of 2078 pathogenic variants from infertility patients' samples across 60 different diseases causing infertility. Additionally, the characteristics of clinically diagnosed infertility patients (i.e. causative variants, laboratory indexes and clinical manifestations) were collected. To the best of our knowledge, the IDDB is the first infertility database serving as a systematic resource for biologists to decipher infertility mechanisms and for clinicians to achieve better diagnosis/treatment of patients from disease phenotype to genetic factors. The IDDB is freely available at http://mdl.shsmu.edu.cn/IDDB/.

[TTV and HPV co-infection in cervical smears of patients with cervical lesions in littoral of Zhejiang province].

OBJECTIVE: To investigate the prevalence of transfusion-transmitted virus (TTV) and human papillomavirus (HPV) co-infection in cervical smears of patients with cervical lesions in littoral of Zhejiang province and analysis of transmitted route. METHODS: Nested polymerase chain reaction (nPCR) was established. TTV DNA were tested by nPCR in cervical smears of 95 patients with cervical lesions and 55 healthy women, paired serum samples were available from 55 and 42 women, and their viral titer. The genotypes of 95 specimens of cervical cytology were detected with HybriMax. The phylogenetic group of TTV was determined by means of nPCR with N22 primers. RESULTS: The prevalence of TTV DNA in cervical smears of patients with cervical lesions and healthy women was 52.7% (29/55) and was comparable with that in paired serum sample (50%). Symptomatic women had significantly higher prevalence of TTV DNA in cervical smears (74.7%) than healthy controls (P = 0.005). The TTV DNA prevalence in patient serum samples was 51%. The phylogenetic groups of TTV serum isolates were concordant with those of TTV from cervical smears of the same subjects, and genotype was G1b. The TTV viral titer in cervical smears were 10 to 1000 times as high as in serum. The total infection rate of HPV was 98.9% in patients, and was 27.3% in healthy women. The frequently detected genotype was HPV16, 18, 33 of HSIL, and HPV6 of LSIL. The HPV positive study subjects had significantly higher TTV DNA prevalence than HPV negatives (P = 0.02). CONCLUSION: High prevalence of TTV in cervical smears suggests that sexual transmission is another mode of expansion of TTV infection among the population. The higher viral titer in cervical smears than in the respective serum samples might indicate active TTV replication in the female genital tract. Nevertheless, cooperation between TTV and HPV needs to be further investigated.