Long-term storage of vitrified oocytes does not affect pregnancy and live birth rates: analysis of 5362 oocyte donation cycles.

Research Question: Does long-term storage of vitrified oocytes affect laboratory and reproductive outcomes after intracytoplasmic sperm injection?

Design: Retrospective cohort study including 41,783 vitrified-warmed oocytes from 5362 oocyte donation cycles between 2013 and 2021. Five categories of storage time were established to analyse its effect on clinical and reproductive outcomes (≤1 year [reference group], 1-2 years, 2-3 years, 3-4 years and >4 years).

Results: The mean number of warmed oocytes was 8.

Exonic genetic variants associated with unexpected fertilization failure and zygotic arrest after ICSI: a systematic review.

Fertilization failure (FF) and zygotic arrest after ICSI have a huge effect on both patients and clinicians, but both problems are usually unexpected and cannot be properly diagnosed. Fortunately, in recent years, gene sequencing has allowed the identification of multiple genetic variants underlying failed ICSI outcomes, but the use of this approach is still far from routine in the fertility clinic. In this systematic review, the genetic variants associated with FF, abnormal fertilization and/or zygotic arrest after ICSI are compiled and analyzed.

No difference in morphokinetics between male and female preimplantation embryos from ART.

Research Question: Do morphokinetic parameters vary between male and female preimplantation embryos?

Design: This was a retrospective cohort study of 175 cycles between March 2018 and June 2021 at two reproductive centres. It included time-lapse data from 92 female and 83 male preimplantation embryos exclusively issued from fresh oocyte donation and undergoing intracytoplasmic sperm injection (ICSI). Only fresh elective single-embryo transfers on day 5 were assessed, and the sex of the embryo was confirmed at birth.

Sperm cryopreservation does not affect live birth rate in normozoospermic men: analysis of 7969 oocyte donation cycles.

Study Question: Does sperm cryopreservation influence the reproductive outcomes of normozoospermic patients in oocyte donation cycles?

Summary Answer: After controlling for confounders, the use of cryopreserved semen from normozoospermic patients does not affect pregnancy and live birth rates after elective ICSI.

What Is Known Already: Sperm cryopreservation by slow freezing is a common practice in ART. While frozen-thawed semen typically presents reduced motility and vitality, its use for ICSI is generally considered adequate in terms of reproductive outcomes.

How long can the sperm wait? Effect of incubation time on ICSI outcomes.

In sperm processing for IVF/ICSI incubation times differ considerably both between and within assisted reproduction facilities. There is no established consensus on the optimal sperm incubation timings to maximize pregnancy rates, and the few studies addressing this association rely on manual and operator-dependent methods for time recording. The present retrospective cohort study includes 1169 ICSI cycles using fresh semen processed by swim-up.

Altered mitochondrial function in spermatozoa from patients with repetitive fertilization failure after ICSI revealed by proteomics.

Background: Unexplained fertilization failure (FF), occurring in 1-3% of intracytoplasmic sperm injection (ICSI) cycles, results in both psychological and financial burden for the patients. However, the molecular causes behind FF remain largely unknown. Mass spectrometry is a powerful technique to identify and quantify proteins across samples; however, no study so far has used it to dissect the proteomic signature of spermatozoa with FF after ICSI.

Novel phospholipase C zeta 1 mutations associated with fertilization failures after ICSI.

Study Question: Are phospholipase C zeta 1 (PLCZ1) mutations associated with fertilization failure (FF) after ICSI?

Summary Answer: New mutations in the PLCZ1 sequence are associated with FFs after ICSI.

What Is Known Already: FF occurs in 1-3% of ICSI cycles, mainly due to oocyte activation failure (OAF). The sperm PLCζ/PLCZ1 protein hydrolyzes phosphatidylinositol (4, 5)-bisphosphate in the oocyte, leading to intracellular calcium release and oocyte activation.

Sperm telomere length in donor samples is not related to ICSI outcome.

Purpose: Variations in sperm telomere length (STL) have been associated with altered sperm parameters, poor embryo quality, and lower pregnancy rates, but for normozoospermic men, STL relevance in IVF/ICSI is still uncertain. Moreover, in all studies reported so far, each man's STL was linked to the corresponding female partner characteristics. Here, we study STL in sperm donor samples, each used for up to 12 women, in order to isolate and determine the relationship between STL and reproductive outcomes.

Is there an association between PAWP/WBP2NL sequence, expression, and distribution in sperm cells and fertilization failures in ICSI cycles?

Successful fertilization in mammals depends on the sperm's ability to initiate intracellular Ca oscillations in the egg, a phenomenon that is elicited by Sperm-oocyte activating factors (SOAFs), whose quantitative and/or qualitative defect might result in fertilization failure. One such proposed factor is Post-acrosomal WW domain-binding protein (PAWP/WBP2NL), although its ability to activate human oocytes has been questioned and its implication in human fertilization failure remains unknown. Here, we sought to determine if PAWP/WBP2NL expression and distribution in sperm cells associate with low/complete fertilization failure in males participating in intracytoplasmic sperm injection (ICSI) cycles.