Association between clinical and IVF laboratory parameters and miscarriage after single euploid embryo transfers.

BACKGROUND: The goal of this study was to investigate which factors, excluding embryo aneuploidies, are associated with miscarriage in patients who have undergone a single euploid blastocyst transfer. METHODS: Retrospective, observational and multicenter study with 2832 patients undergoing preimplantational genetic testing for aneuploidies (PGT-A) due to repeated implantation failure, recurrent pregnancy loss, advanced maternal age or severe male factor were transferred one single euploid embryo. RESULTS: One of the main findings was a significant relationship between body mass index (BMI) and miscarriage rates (13.4% in underweight women, 12.1% in normal weight, 14.5% in overweight, and 19.2% in obese women, odds ratio [OD] 1.04; 95% confidence interval [CI], 1.01-1.07 p = 0.006). Endometrial thickness (OD 0.65; 95%, 0.52-0.77 p = 0.04) and type of endometrial preparation (natural cycle or hormone replacement cycle) (OD 0.77; 95%, 0.52-0.77, p = 0.04) were also associated with miscarriage rates. CONCLUSIONS: BMI was strongly associated to miscarriage rates. We also observed a weaker association with endometrial thickness and with the type of endometrial preparation (natural cycle or hormone replacement cycle). None of the other studied variables (biopsy day, maternal and male age, duration of infertility, cycle length, previous miscarriages, previous live births, previous In Vitro Fertilization (IVF) cycles, endometrial pattern and/or diagnosis) were associated with miscarriage rates.

Type of chromosome abnormality affects embryo morphology dynamics.

OBJECTIVE: To study the differences in the cleavage time between types of embryo chromosomal abnormalities and elaborate algorithm to exclude aneuploid embryos according to the likelihood to be euploid. DESIGN: Retrospective cohort study. SETTING: University affiliated private center. PATIENT(S): Preimplantational genetic screening patients (n = 112) including cases of advanced maternal age, repeated implantation failure, and recurrent miscarriage. A total of 485 embryos were analyzed. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): All biopsied embryos were cultured in an incubator with time-lapse technology, cleavage timing from insemination to day 3 and all kinetic parameters that have been described in previous studies by our group. RESULT(S): Logistic regression analysis were used to identify morphokinetic parameters and some were strongly associated with complex aneuploid embryos; t3 (odds ratio = 0.590, 95% confidence interval 0.359-0.971) and t5-t2 (odds ratio = 0.151, 95% confidence interval 0.082-0.278). CONCLUSION(S): Embryo morphokinetics are affected by chromosome aneuploidy and further analysis of the chromosome content reveals higher differences when the complexity in the chromosome disorders is increased. The use of time-lapse monitoring, although not able to detect an abnormal embryo, may be potentially useful to discard those embryos with high risk of complex chromosomal abnormalities.

Oocyte versus embryo vitrification for delayed embryo transfer: an observational study.

The aim of this observational prospective study was to compare multiple embryological and pregnancy outcomes for vitrified oocytes against the same outcomes using vitrified embryos in patients at risk for ovarian hyperstimulation syndrome. Ninety-six patients were included and allocated to vitrification of oocytes (Group 1) or embryos (Group 2). No statistical differences in baseline characteristics between groups were detected. Implantation rate was 30.6% versus 33.1%, and clinical pregnancy rate was 41.9% versus 7.1% in groups 1 and 2, respectively. A higher clinical spontaneous abortion rate occurred in group 2 (9.7% versus 21.9% for groups 1 and 2, respectively), but the same cumulative clinical pregnancy rate was observed after three embryo transfers (62.0% in group 1 and 69.6% in group 2). The ongoing pregnancy rate per patient was similar in both groups (56.0% and 54.3% in groups 1 and 2, respectively). Also, live birth rate per stimulation was similar (72.0% and 69.6% in groups 1 and 2, respectively). No differences were observed in outcomes according to vitrification timing. Oocyte vitrification achieved the same live birth rate as embryo vitrification.

The impact of in-vitro maturation of oocytes on aneuploidy rate.

Chromosome abnormalities in embryos obtained through in-vitro maturation (IVM) of oocytes from 11 oocyte donors were compared with embryos from women undergoing fluorescence in-situ hybridization (FISH) analysis for sex selection. Thirty-three oocytes had reached metaphase II stage at 28-30 h (65%) and 27 were successfully fertilized by intracytoplasmic sperm injection. Blastomere biopsy was performed in 20 embryos (74%). For five embryos, two blastomeres were analysed, three of which were mosaic. FISH study revealed aneuploidies of chromosomes 13, 15, 16, 18, 21, 22, X and Y in 12 embryos (60%) and euploidy in the remaining eight (40%). The percentage of aneuploidies in the control group was 33%. Differences between IVM and control embryos were not statistically significant. The high incidence of chromosome abnormalities in embryos resulting from the IVM protocol may account for the low implantation rates reported by others. Although a greater incidence of miscarriage or congenital abnormalities in babies born alive following IVM versus conventional IVF has not been observed in previous studies, preimplantation genetic aneuploidy screening or prenatal chromosome studies may be recommended to these patients on the basis of the present results.