Testicular sperm is increasingly used during in vitro fertilization treatment. Testicular sperm has the ability to fertilize the oocyte after intracytoplasmic sperm injection (ICSI), but they have not undergone maturation during epididymal transport. Testicular sperm differs from ejaculated sperm in terms of chromatin maturity, incidence of DNA damage and RNA content. It is not fully understood what the biological impact is of using testicular sperm, on fertilization, preimplantation embryo development and post-implantation development. Our goal was to investigate differences in human preimplantation embryo development after ICSI using testicular sperm (TESE-ICSI) and ejaculated sperm. We used time-lapse embryo culture to study these possible differences. Embryos (n = 639) originating from 208 couples undergoing TESE-ICSI treatment were studied and compared to embryos (n = 866) originating from 243 couples undergoing ICSI treatment with ejaculated sperm. Using statistical analysis with linear mixed models, we observed that pronuclei appeared 0.55 hours earlier in TESE-ICSI embryos, after which the pronuclear stage lasted 0.55 hours longer. Also, significantly more TESE-ICSI embryos showed direct unequal cleavage from the 1-cell stage to the 3-cell stage. TESE-ICSI embryos proceeded faster through the cleavage divisions to the 5- and the 6-cell stage, but this effect disappeared when we adjusted our model for maternal factors. In conclusion, sperm origin affects embryo development during the first embryonic cell cycle, but not developmental kinetics to the 8-cell stage. Our results provide insight into the biological differences between testicular and ejaculated sperm and their impact during human fertilization.

To study the impact of culture media on preimplantation morphokinetics used for predicting clinical outcomes. All IVF and ICSI cycles performed between 2012 and 2017 with time-lapse information available were included. In November 2014, culture medium was changed from Vitrolife G-1 PLUS to SAGE 1-Step. Each embryo was retrospectively assigned a morphokinetic-based KIDScore for prediction of implantation. Clinical outcomes were retrieved from medical records. Linear mixed models were used to study differences in morphokinetic parameters, a proportional odds model for KIDScore ranking and logistic regression for differences in clinical outcomes. All analyses were adjusted for patient and treatment characteristics. In 253 (63.1%) cycles, embryos (n = 671) were cultured in Vitrolife, and in 148 (36.9%) cycles, embryos (n = 517) were cultured in SAGE. All cleavage divisions occurred earlier for SAGE embryos than for Vitrolife embryos (2-cell: -2.28 (95%CI: -3.66, -0.89), 3-cell: -2.34 (95%CI: -4.00, -0.64), 4-cell: -2.41 (95%CI: -4.11, -0.71), 5-cell: -2.54 (95%CI: -4.90, -0.18), 6-cell: -3.58 (95%CI: -6.08, -1.08), 7-cell: -5.62 (95%CI: -8.80, -2.45) and 8-cell: -5.32 (95%CI: -9.21, -1.42) hours, respectively). Significantly more embryos cultured in SAGE classified for the highest KIDScore compared to embryos cultured in Vitrolife (p < 0.001). No differences were observed in clinical outcomes. Our results demonstrate an impact of culture medium on preimplantation embryo developmental kinetics, which affects classification within the KIDScore algorithm, while pregnancy outcomes were comparable between the groups. This study underscores the need to include the type of culture medium in the development of morphokinetic-based embryo selection tools.

Study question Is there an association between neighbourhood socioeconomic status (SES) and cumulative ongoing pregnancy after 2.5 years of in vitro fertilization (IVF) treatment? Summary answer Low and middle neighbourhood SES is associated with lower odds of an ongoing pregnancy within 2.5 years of IVF treatment than high neighbourhood SES. What is known already Low SES is known to have a negative impact on general health and a variety of medical conditions, including perinatal health. However, not much data is available on the impact of SES on IVF treatment outcome. Study design, size, duration This is a retrospective observational study of 3720 couples undergoing IVF or IVF-ICSI treatment between 2006 and 2020. Participants/materials, setting, methods Neighbourhood SES was assigned to each couple based on the postal code of residence. Subsequently, SES was categorized into low (&lt;p20), medium (p20-p80), and high (&gt;p80). Multivariable logistic regression analyses were performed with cumulative ongoing pregnancy within 2.5 years as outcome variable, SES category, female age, BMI, smoking status (yes/no), and interaction terms for age*SES and BMI*SES were used as covariates. Main results and the role of chance There was no difference in ongoing pregnancy rates between SES groups after the first fresh embryo transfer or in the average number of IVF treatment cycles performed. However, the cumulative ongoing pregnancy rates differ significantly between SES groups (Low; 43.6%, medium; 50.9%, high; 54.1%). Low SES had significantly lower odds for achieving an ongoing pregnancy within 2.5 years (OR = 0.06 (95%CI 0.02-0.22)). The interaction terms age*SES and BMI*SES showed attenuation of this association with increasing age and BMI (OR = 1.07 (95%CI 1.022 – 1.12) and OR = 1.61 (95%CI 1.25 – 2.09), respectively). The associations with medium SES were similar, but less pronounced (OR = 0.16 (95%CI 0.05 – 0.50) with OR = 1.04 (95%Cl 1.00 – 1.09) and OR = 1.41 (1.12 – 1.77) for the interaction terms with female age and BMI respectively. Limitations, reasons for caution We were not able to perform additional analysis on individual characteristics like educational level, ethnicity or language proficiency due to lack of data. Wider implications of the findings In the Netherlands, health insurance is mandatory. Our study showed that even with equal access to fertility care, patients living in a low SES neighbourhood are disadvantaged. This underlines the importance of taking the whole wellbeing of the patient into account, before starting an IVF treatment. Trial registration number not applicable