We conducted a genome-wide association study in a large population of infertile men due to unexplained spermatogenic failure (SPGF). More than seven million genetic variants were analysed in 1,274 SPGF cases and 1,951 unaffected controls from two independent European cohorts. Two genomic regions were associated with the most severe histological pattern of SPGF, defined by Sertoli cell-only (SCO) phenotype, namely the MHC class II gene HLA-DRB1 (rs1136759, P = 1.32E-08, OR = 1.80) and an upstream locus of VRK1 (rs115054029, P = 4.24E-08, OR = 3.14), which encodes a protein kinase involved in the regulation of spermatogenesis. The SCO-associated rs1136759 allele (G) determines a serine in the position 13 of the HLA-DRβ1 molecule located in the antigen-binding pocket. Overall, our data support the notion of unexplained SPGF as a complex trait influenced by common variation in the genome, with the SCO phenotype likely representing an immune-mediated condition.

The application of MACS non-apoptotic sperm selection in infertility clinics is controversial since the published literature does not agree on its effect on reproductive outcomes. Therefore, it is not part of the routine clinical practice. Classical measures of reproductive success (pregnancy or live birth rates per ovarian stimulation) introduce a bias in the evaluation of a technique’s effect, since only the best embryo is transferred. This retrospective, multicenter, observational study evaluated the impact of MACS on reproductive outcomes, measuring results in classical parameters and cumulative live birth rates (CLBR). Data from ICSI cycles using autologous oocyte in Spanish IVIRMA fertility clinics from January 2008 to February 2020 were divided into two groups according to their semen processing: standard practice (reference: 46,807 patients) versus an added MACS sperm selection (1779 patients). Only when measured as CLBR per embryo transferred and per MII oocyte used was the difference between groups statistically significant. There were no significant differences between MACS and reference groups on pregnancy and live birth rates. In conclusion, results suggest that non-apoptotic sperm selection by MACS on unselected males prior to ICSI with autologous oocytes has limited clinical impact, showing a subtle increase in CLBR per embryo transferred.

Purpose: To ascertain whether physical activity (PA) is associated with better sperm quality in sperm donors. Methods: A prospective case–control study was designed in an IVF center setting. A total of 207 sperm donation candidates from a relatively small geographical area were included in the study with no intervention. Donor candidates were subjected to conventional sperm analysis according to WHO criteria. Moreover, they answered a standardized questionnaire regarding their last week PA (IPAQ), with PA expressed in metabolic equivalents (METs)-min/week. Donors were classified into 4 groups: low, moderate, high and very high PA. Specific sports were included in the questionnaire. Semen samples from 43 accepted donors were used in artificial insemination by donor (AID) and IVF. The fertilization rates (FR) and pregnancy rates (PR) were studied. Results: Semen volume, sperm concentration, progressive spermatozoa, non-progressive spermatozoa, total motile progressive spermatozoa and sperm morphology were similar in the four PA groups. No correlation between various semen parameters studied and METs was found. Running or cycling > 1 h/week did not influence sperm parameters. The AID PR was similar in the different PA groups. However, in IVF the mean donor FR was significantly higher in the high PA group and in the very high PA group. Conclusions: No detrimental effect was associated with PA, or even very high PA, regarding conventional sperm parameters. Moreover, a better FR was associated with high and very high PA in IVF cycles, which merits more studies.

In lesbian couples, is shared motherhood IVF (SMI) associated with an increase in perinatal complications compared with artificial insemination with donor sperm (AID)? Singleton pregnancies in SMI and AID had very similar outcomes, except for a non-significant increase in the rate of preeclampsia/hypertension (PE/HT) in SMI (recipient’s age-adjusted odds ratio (OR) = 1.9, 95% CI = 0.7–5.2; P = 0.19), but twin SMI pregnancies had a much higher frequency of PE/HT than AID twins (recipient’s age-adjusted OR = 21.7, 95% CI = 2.8–289.4; P = 0.01). Oocyte donation (OD) pregnancies are associated with an increase in perinatal complications, in particular, preterm delivery and low birth weight, and PE/HT. However, it is unclear to what extent these complications are due to OD process or to the conditions why OD was performed, such as advanced age and underlying health conditions. Unfortunately, the literature concerning perinatal outcomes in SMI is scarce. Retrospective study involving 660 SMI cycles (299 pregnancies) and 4349 AID cycles (949 pregnancies) assisted over a 10-year period. All cycles fulfilling the inclusion criteria performed in lesbian couples seeking fertility treatment in 17 Spanish clinics of the same group. Pregnancy rates of SMI and AID cycles were compared. Perinatal outcomes were compared: gestational length, newborn weight, preterm and low birth rates, PE/HT rates, cesarean section rates, perinatal mortality, and newborn malformations. Pregnancy rates were higher in SMI than in AID (45.3% versus 21.8%, P < 0.001). There was a non-significant trend to higher multiple rate in AID (4.7% versus 8.5%, P = 0.08). In single pregnancies, there were no differences between SMI and AID in gestational age (278 days (268–285) versus 279 (272–284), P = 0.24), preterm rate (8.3% versus 7.3%, P = 0.80), preterm <28 weeks (0.6% versus 0.4%, P = 1.00), newborn weight (3195 g (2915–3620) versus 3270 g (2980–3600), P = 0.296), low birth rate (6.4% versus 6.4%, P = 1.00), extremely low birth weight (0.6% versus 0.5%, P = 1.00), and the distribution of newborns by weight groups. Cesarean section rate, newborn malformation rate, and perinatal mortality were also similar in SMI and AID. Additionally, there was non-significant trend in hypertensive disorders to an increase in PE/HT among SMI (recipient’s age-adjusted OR = 1.9, 95% CI = 0.7–5.2). Overall, perinatal data are consistent with what is reported in the general population. In twin pregnancies, the aforementioned perinatal parameters were also very similar in SMI and AID. However, SMI twin pregnancies had a very high risk of PE/HT when compared with AID (recipient’s age-adjusted OR = 21.7, 95% CI = 2.8–289.4, P = 0.01). Our data regarding the pregnancy course were obtained from information registered in the delivery report as well as from what was reported by the patients themselves, so a certain degree of inaccuracy cannot be ruled out. Additionally, in some parameters, there was up to 10% of data missing. However, since the methodology of reporting was the same in SMI and AID groups, one should not expect a differential reporting bias. It cannot be ruled out that the risk of PE/HT in simple gestations would be significant in a larger study. Additionally, in the SMI group allocation to the transfer of 2 embryos was not randomized so some bias is possible. SMI, if single embryo transfer is performed, seems to be is a safe procedure. Double embryo transfer should not be performed in SMI. Our data suggest that the majority of complications in OD could be related more with recipient status than with OD itself, since with SMI (performed in women without fertility problems) the perinatal complications were much lower than usually described in OD. No external funding was received. The authors declare that they have no conflict of interest. N/A.

Objectives: To assess if the instillation of plasma rich growth factors (PRGFs) improves endometrial thickness (EMT) in frozen embryo cycles performed under hormone treatment where the endometrium was very thin (≤5 mm). Methods: First, a randomized controlled trial (RCT) was performed comparing women only receiving an increase in estrogen therapy (n = 9) and women receiving both the increase in estrogen therapy and three instillations of PRGF (n = 13). The second part of the study consisted of a prospective observational follow-up of the patients included in the RCT (for 1–3 months in the study group, and for 1–6 months in the control group). Results: In the RCT, there was an increase in EMT in both the PRGF and control groups. However, the increase was significantly higher in the PRGF group (1.30 ± 0.67 mm) compared to the control group (0.58 ± 0.51 mm). In the PRGF group, 23% achieved an EMT of 7 mm compared to 0% in the control group. There were 2 pregnancies in the PRGF group resulting from the 3 transfers performed in that group. No transfer was carried out in the control group. There was a significant increase in EMT 1–3 months after the PRGF cycle. The live birth rate per transfer was 20% in the cycles following the PRGF cycles, whereas it was 30% per starting woman. For women in the control group who later underwent PRGF, the LBR was 57.1%. Conclusions: PRGF instillation in cases of very thin endometrium increases EMT moderately. It is suggested that the beneficial effect of PRGF may persist for 1–3 cycles after instillation.

STUDY QUESTION: What is the functional impact of the rs508485 genetic polymorphism, located in the 3′-untranslated region (UTR) region of the PIWIL4 gene, on non-obstructive azoospermia (NOA)? SUMMARY ANSWER: The rs508485 genetic variant contributes to the pathogenesis of extreme patterns of NOA by modulating PIWIL4 expression through microRNA (miRNA) interactions. WHAT IS KNOWN ALREADY: Male infertility represents a significant global health challenge with profound societal and economic consequences. One of the most severe forms of male infertility is NOA, which is characterized by severe spermatogenic failure (SPGF) of idiopathic origin in most cases. Cumulating knowledge increasingly suggests that this idiopathic form of NOA may represent a multifactorial condition involving complex interactions between genetic and environmental factors. The PIWI protein subfamily, particularly PIWIL4, plays a pivotal role in spermatogenesis by processing PIWI-interacting RNAs, which silence retrotransposons to protect genomic integrity. Genetic variations in this gene have been found to be associated with susceptibility to NOA. STUDY DESIGN, SIZE, DURATION: A case–control study was conducted in a European cohort including 1516 infertile men with SPGF and 2451 fertile controls. Logistic regression and functional assays were employed to investigate the functional role of the rs508485 polymorphism in PIWIL4. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were genotyped for the rs508485 polymorphism. Associations between the polymorphism and NOA phenotypes, including Sertoli cell-only (SCO) syndrome and testicular sperm extraction (TESE) outcomes, were assessed. In silico tools predicted miRNA binding effects, which were subsequently validated using luciferase reporter assays. MAIN RESULTS AND THE ROLE OF CHANCE: The T allele of rs508485 was significantly associated with the SCO phenotype (P = 2.69E-03, OR = 1.34) and unfavourable TESE outcomes (P = 1.09E-03, OR = 1.54). In silico analyses predicted that the rs508485 variant might alter binding sites in the 3′-UTR region of PIWIL4 for different miRNAs, such as hsa-miR-215-3p and hsa-miR-136-3p. Functional validation using luciferase assays confirmed that these miRNAs differentially bind to the T and C alleles of this polymorphism, influencing PIWIL4 regulation. LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: The study is limited to a single genetic polymorphism and functional assays were performed in vitro. Additional studies are required to validate these findings across diverse populations and explore additional genetic interactions. WIDER IMPLICATIONS OF THE FINDINGS: These findings highlight the critical role of miRNA regulation in extreme forms of male infertility by influencing the expression of essential spermatogenesis genes, such as PIWIL4. Our study sheds light on the genetic mechanisms underlying spermatogenesis and suggests potential therapeutic targets for NOA. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the Spanish Ministry of Economy and Competitiveness through the Spanish National Plan for Scientific and Technical Research and Innovation (grant: PID2020-120157RB-I00 funded by MICIU/AEI/10.13039/501100011033; and grant: PID2023-152215OB-I00 funded by MICIU/AEI/10.13039/501100011033 and ERDF, EU). M.C.-M is beneficiary of a Juan de la Cierva 2022 postdoctoral fellowship (reference number JDC2022-048561-I) funded by MCIN/AEI/10.13039/501100011033 and European Union NextGenerationEU/PRTR. S.L. received support from “Generalitat de Catalunya” (grant 2021SGR052). S.L. is sponsored by the “Researchers Consolidation Program” from the SNS-Dpt. Salut Generalitat de Catalunya (Exp. CES09/020). S.G.-M. was funded by grant ref. FPU23/02674. S.S. was supported by funds from the Portuguese Foundation for Science and Technology (FCT; 10.54499/DL57/2016/CP1363/CT0019). The authors declare no competing interests.