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Human Reproduction

Oxford University Press (OUP)

Preprints posted in the last 30 days, ranked by how well they match Human Reproduction's content profile, based on 11 papers previously published here. The average preprint has a 0.08% match score for this journal, so anything above that is already an above-average fit.

1
Fertile-window misclassification in period-tracking applications and associated pregnancy risk: a large observational analysis

Brondolin, E.; Hadengue, B.; Perro, D.; Gemzell-Danielsson, K.; Granne, I.; Nguyen, B. T.; Costescu, D.; Berglund Scherwitzl, E.; Scherwitzl, R.; Krauss, K.; Benhar, E.

2026-02-14 obstetrics and gynecology 10.64898/2026.02.12.26346180
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ObjectivesGiven the widespread use of period-tracking applications and evidence that some users rely on fertile-window predictions for pregnancy prevention, we aimed to quantify pregnancy risk arising from misclassification of biologically fertile days by period-tracking applications, and to compare this risk across calendar-based and basal body temperature (BBT)-supported period tracking and a digital contraceptive regulated as a medical device. MethodsWe conducted an observational analysis of cycles of mobile fertility application users who logged urinary luteinizing hormone (LH) tests. Biologically fertile days were defined using an LH-based reference fertile window (days -5 to 0 relative to ovulation). Three approaches were evaluated: a calendar-based period tracking application, a BBT-supported period tracking application, and a FDA-cleared digital contraceptive. Outcomes included day-specific frequency of fertile days misclassified as safe, cycle-level misclassification, and predicted pregnancy risk per cycle. Analyses were repeated in a subgroup of irregular cycles. Results543,167 menstrual cycles with a clear LH surge signature were included in the analysis. Calendar-based period tracking frequently misclassified fertile days as safe, with 67% of cycles containing at least one at-risk day and 25% containing at least one high-risk day. The mean predicted pregnancy risk per cycle was 22%, increasing to 65% in irregular cycles. BBT-supported period tracking reduced misclassification but remained associated with substantial risk (41% of cycles with at least one at-risk day; mean predicted pregnancy risk 9%). In contrast, the digital contraceptive showed consistently low misclassification (3% of cycles with any at-risk day and a mean predicted pregnancy risk of 0.5%). ConclusionsBoth calendar-based and BBT-supported period-tracking applications not intended for contraception frequently misclassify biologically fertile days and should not be considered reliable tools for pregnancy prevention. Regulated digital contraceptives demonstrate substantially lower pregnancy risk. Short condensationPeriod-tracking apps frequently misclassify fertile days as safe, including days with high pregnancy risk. In a large real-world analysis, both calendar- and BBT-supported trackers showed substantial risk, unlike digital contraception methods regulated as a medical device.

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Semaglutide alters the human embryo-endometrium interface

Apostolov, A.; Pathare, A. D. S.; Lavogina, D.; Zhao, C.; Kask, K.; Blanco Rodriguez, L.; Ruiz-Duran, S.; Risal, S.; Rooda, I.; Damdimopoulou, P.; Saare, M.; Peters, M.; Koistinen, H.; Acharya, G.; Zamani Esteki, M.; Lanner, F.; Sola Leyva, A.; Salumets, A.

2026-03-07 obstetrics and gynecology 10.64898/2026.03.03.26347354
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The use of semaglutide (SE), a glucagon-like peptide-1 receptor agonist (GLP-1RA) with glucose-lowering and weight-loss effects, has risen rapidly, particularly among women of reproductive age. While preclinical studies suggest benefits for ovarian function via the hypothalamic-pituitary-ovarian axis, its impact on the endometrial-embryo interface remains unclear. Here, we show that GLP-1R is dynamically expressed in fertile human endometrium, restricted to epithelial cells and markedly upregulated during the mid-secretory phase of the menstrual cycle. In a preclinical model of endometrial epithelial organoids, SE at physiological concentrations activates intracellular cAMP signaling, enhances epithelial metabolism, and upregulates receptivity markers without steroid hormone priming, whereas higher concentrations modestly reduce expression of a key receptivity marker PAEP/glycodelin and shift metabolism towards oxidative phosphorylation. By contrast, in stromal cells lacking detectable GLP-1R, SE disrupts decidualization, induces endoplasmic reticulum stress and suppresses cell-cycle at G2/M phase. Human embryo models, blastoids, expressed GLP-1R and underwent concordant SE-mediated transcriptional remodeling in epiblast and trophectoderm lineages, encompassing changes in metabolism and epigenetic regulation, but without shifts in lineage proportions. Notably, SE increased blastoid attachment to the endometrial epithelium in the absence of exogenous steroid hormones, suggesting enhanced epithelial-embryo interaction. Together, these findings reveal a compartment-specific mismatch, as SE augments epithelial and embryonic metabolic activity but compromises stromal support for implantation, with potential consequences for implantation due to stromal dysfunction.

3
HIPK4 is a novel gene associated with teratozoospermia and male infertility

Koser, S. A.; Rieck, C.; Aprea, I.; Krallmann, C.; Gaikwad, A. S.; Wallmeier, J.; Tenardi-Wenge, R.; Di Persio, S.; Neuhaus, N.; Raidt, J.; Omran, H.; Laurentino, S.; Kliesch, S.; Stallmeyer, B.; Friedrich, C.; Tüttelmann, F.

2026-03-04 sexual and reproductive health 10.64898/2026.03.04.26346694
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STUDY QUESTIONAre pathogenic variants in Homeodomain-interacting protein kinase (HIPK4) associated with sperm head abnormalities causing male infertility? SUMMARY ANSWERHIPK4 is a novel candidate gene associated with sperm head defects and human male infertility. WHAT IS KNOWN ALREADYNumerous genes causing male infertility due to Multiple Morphological Abnormalities of the sperm flagella (MMAF) have been described but the genetic basis of sperm head defects is less well understood. STUDY DESIGN, SIZE, DURATIONFour infertile brothers displaying varying degrees of quantitatively and/or qualitatively impaired spermatogenesis, their parents, and their fertile brother were included in the study. Further, the Male Reproductive Genomics (MERGE) cohort comprising exome/genome sequencing data of >3,300 men was queried. PARTICIPANTS/MATERIALS, SETTING, METHODSWe performed exome sequencing in all five brothers and their parents. To characterise the sperm phenotype, standard semen analysis, immunofluorescence staining, and transmission-electron microscopy (TEM) were carried out. Further, we evaluated the impact of the HIPK4 variant in cell culture experiments using HEK293T cells. MAIN RESULTS AND THE ROLE OF CHANCEAnalysing the exome data, we could not identify a common genetic cause in all four affected brothers. However, one of the affected brothers was compound heterozygous for two loss-of-function variants in DNAH17 (c.1076_1077dup p.(Lys360*) and c.7752+2T>A p.?) associated with markedly reduced sperm motility and MMAF. The variants pathogenicity was further validated by TEM of flagellar cross-sections revealing an outer dynein arm defect and axonemal disruption. On the contrary, his three infertile brothers were homozygous for the start-loss variant c.1A>G in HIPK4. This gene is expressed during spermiogenesis and is reportedly involved in sperm head shaping in mice. Heterologous expression of (partial) HIPK4 variant cDNA elucidated the alternative use of an in frame start codon located 35 amino acids downstream, resulting in an N-terminally truncated protein p.(Met1_Glu35del). The truncated HIPK4 protein lacks parts of its kinase domain and shows reduced protein stability. In line with published mouse models, all three brothers displayed 100% abnormal sperm head morphology with variable defects. Importantly, one brother affected by HIPK4 variants fathered a child after successful intracytoplasmic sperm injection demonstrating that it is a treatment option for HIPK4-related teratozoospermia. No further men from the MERGE cohort were affected by biallelic HIPK4 variants. Taken together, HIPK4 is an autosomal-recessive candidate gene associated with sperm head defects and male infertility. LARGE SCALE DATAThe reported variants in DNAH17 and HIPK4 were submitted to ClinVar. LIMITATIONS, REASONS FOR CAUTIONIndependent replication is required to assess the phenotypic spectrum and the reproductive outcome associated with biallelic HIPK4 variants and to formally establish the gene-disease relationship for male infertility. WIDER IMPLICATIONS OF THE FINDINGSThis study raises awareness of the significant genetic heterogeneity of male infertility. The described family highlights that distinct genetic causes may underlie a seemingly similar phenotype. Exome sequencing of families is helpful to efficiently disentangle individual causes among affected family members. STUDY FUNDING/COMPETING INTEREST(S)N.N., J.R., H.O., S.L., C.F., and F.T. were supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the Clinical Research Unit Male Germ Cells (CRU326, project number 329621271). R.T.W., N.N., J.R., H.O., and F.T. were supported by the Federal Ministry of Research, Technology and Space (BMFTR) as part of the project ReproTrack.MS (grant 01GR2303). S.A.K. was supported by the DFG Clinician Scientist programme CareerS Munster (project number 493624047). A.S.G. was supported by the Medical Faculty Munster via an Innovative Medical Research (IMF) grant (GA-122104).

4
Large-scale genome-wide analyses of proteomic data identifies that sex hormones affect plasma glycodelin levels

McDowell, S.; Beaumont, R. N.; Green, H.; Kingdom, R.; Vabistsevits, M.; Prague, J. K.; Murray, A.; Tyrrell, J.; Ruth, K. S.

2026-03-06 sexual and reproductive health 10.64898/2026.03.06.26347586
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Study question: How is glycodelin, a glycoprotein secreted by reproductive tissues, causally related to reproductive diseases and traits? Summary answer: We present evidence for a causal role of sex hormones in determining glycodelin levels, but limited evidence that glycodelin subsequently causally impacts reproductive traits. What is known already: Glycodelin is expressed in female and male reproductive tissues and has four glycoforms (-A, -C, -F and -S), with the glycosylation pattern determining its function. Differences in the levels of glycodelin are associated with reproductive traits, including fertility, endometriosis, preeclampsia, and female-specific malignancies. Study design, size, duration: We used cross-sectional data from the UK Biobank to investigate relationships between glycodelin and reproductive-related traits in men and women by performing genome-wide association studies (GWAS) and Mendelian randomization (MR) analyses. Participants/materials, setting, methods: We included individuals of European genetic ancestry aged 40-69 in 2006-2010, with genetic data in the UK Biobank v3 release. We performed GWAS of glycodelin levels in 46,468 people, stratified by sex (21,368 men and 25,100 women) and menopause status (6,409 pre- and 18,691 post-menopausal women). We tested bidirectional casual associations between glycodelin levels and 19 reproductive-related traits using one- and two-sample MR analyses. Main results and the role of chance: Nine genetic signals reached genome-wide significance (P<5x10-8) across the glycodelin phenotypes. A known genetic signal (rs9409964) near the PAEP gene, which encodes glycodelin, was most strongly associated (P<3x10-80 across all phenotypes), and had heterogeneous effects (effect (SD) per A allele of 1.31 in men vs 0.60 in women, and 0.4 in pre- vs 0.9 in post-menopausal women). Higher serum concentrations of bioavailable testosterone raised glycodelin in men (effect = 0.14 SD, IVW P=4.1x10-13), while effects in women depended on menopause status (pre-menopausal effect = -0.16 SD, IVW P=3.6x10-3; post-menopausal effect = 0.10 SD, IVW P=5.9x10-4). There was no strong evidence that differences in glycodelin levels were caused by, or were the cause of, other reproductive-related traits. Limitations, reasons for caution: Proteomic measurements of glycodelin did not differentiate between glycoforms and were derived from blood and might not reflect levels in reproductive tissues. The sample size for the pre-menopausal GWAS was modest, reducing our power to detect relationships with reproductive conditions. Genetic instruments are assumed to be proxies for average lifelong exposure, which does not reflect variation in hormones and biomarkers over lifetime. Wider implications of the findings: We suggest that reported associations of glycodelin with reproductive conditions are likely to result from the effects of sex hormones rather than being directly causal. These findings may help reconcile previously conflicting associations between glycodelin and reproductive traits.

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The landscape of structural variants in male infertility identified by optical genome mapping

Kovanda, A.; Hodzic, A.; Kotnik, U.; Visnjar, T.; Podgrajsek, R.; Andjelic, A.; Jaklic, H.; Maver, A.; Lovrecic, L.; Peterlin, B.

2026-03-02 genetic and genomic medicine 10.64898/2026.02.27.26347236
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STUDY QUESTION[Do structural genomic variants, that can be identified by using optical genome mapping, contribute to male infertility?] SUMMARY ANSWER[By using optical genome mapping we can identify several types of structural variants, both known and new, that may contribute to male infertility.] WHAT IS KNOWN ALREADY[Traditional approaches such as karyotyping, CFTR and chromosome Y microdeletion testing are successful in explaining clinical findings in [~]30% of MI patients, leaving the rest without a genetic diagnosis. Recent research suggests at least 265 genes may play a role in male fertility. While the assessment of the roles of copy number variants and single nucleotide variants in monogenic forms of disease in these genes is underway, much less is known about structural variants.] STUDY DESIGN, SIZE, DURATION[We performed a longitudinal case/control study on a total of 220 individuals; 88 patients with male infertility, negative for cytogenetic abnormalities using karyotyping, and molecular testing for chrY microdeletions, and CFTR gene variants, and 132 healthy male individuals that underwent optical genomic mapping for other reasons. Exclusion criteria for the control cohort were low-sperm quality and/or inclusion in IVF procedures. The study was approved by the National Medical Ethics Committee of the Republic of Slovenia (reference number: 0120-213/2022/6). Optical genome mapping was performed from an aliquot of whole blood collected for routine testing purposes at the Clinical Institute of Genomic Medicine (CIGM), UMC Ljubljana from January 2023 to November 2024.] PARTICIPANTS/MATERIALS, SETTING, METHODS[We examined structural variants in 220 participants by using optical genome mapping, which was performed with DLE-1 SP-G2 chemistry and the Saphyr instrument. The de novo assembly and Variant Annotation Pipeline were executed on Bionano Solve3.7_20221013_25 while reporting and direct visualization of structural variants was done on Bionano Access 1.7.2. All obtained variants were filtered using the Bionano Access software and in-house generated gene/regions of interest panel bed files. The first filter was applied to include variants below a population frequency of 10%, and overlapping the regions of interest. Subsequently, all variants occurring with frequency 0% in the internal manufacturer variant dataset were manually evaluated for possible involvement of the overlapping genes or regions in biological processes involved in MI. The male infertility cohort also underwent research whole exome analyses as previously reported. All results of optical genomic mapping were confirmed by an appropriate alternative method where available.] MAIN RESULTS AND THE ROLE OF CHANCE[We show that the overall number of structural variants in MI patients does not differ from that of healthy individuals. By looking in detail at genes and regions associated with MI, we identified 21 rare variants absent from controls in 25.0 % of MI patients, of which five were likely causative, and two would be missed by using traditional approaches. These variants include inversions, duplications, amplifications, deletions (e.g. SPAG1), and insertions/expansions (e.g. DMPK), that were validated using additional methods. While the remaining SV cannot be currently classified as pathogenic according to existing criteria, they open a new avenue in genetic research of MI. LARGE SCALE DATA[Variants reported in this study were deposited into ClinVar under accession numbers SUB15650956 (https://www.ncbi.nlm.nih.gov/clinvar/)] LIMITATIONS, REASONS FOR CAUTION[Technical limitations of optical genome mapping include the lack of DLE-1 labelling of centromeric and telomeric regions, the inability to detect Robertsonian translocations, the unclear exact location of smaller structural variants located between the DLE-1 labels, and unclear boundaries in case of their location in segmentally duplicated regions (this limitation is shared with other methods). The ACGM criteria of rarity are also hard to apply, as the fertility status of the individuals in healthy population databases such as GnomAD and DGV is unknown. Similarly, gene-associated phenotype and the proposed inheritance model both need to be considered as parts of the ACMG criteria, but for many candidate genes associated with MI, no model of inheritance has yet been proposed.] WIDER IMPLICATIONS OF THE FINDINGS[Currently, with the established diagnostic approaches we are able to resolve [~]30% of male infertility cases, with [~]70% of patients remaining undiagnosed. The significance of our work is in showing that rare structural variants can be identified in MI, by using optical genome mapping, opening new avenues of research of the genetics of this important contributor to human fertility.] STUDY FUNDING/COMPETING INTEREST(S)[All authors declare having no conflict of interest in regard to this research. This work was funded by the Slovenian Research and Innovation Agency (ARIS) Programme grant P3-0326: Gynecology and Reproduction: Genomics for personalized medicine] Lay summaryMale infertility affects about 5% of adult males and has complex causes, including genetic ones, such as mutations in the CFTR gene, small deletions on chromosome Y, and balanced translocations, but currently we can only find a genetic cause in [~]30% of patients. This means [~]70% of cases remain undiagnosed but potentially, they too may have a yet unknown genetic cause. Indeed, so far research has shown at least 265 genes have been proposed to play a role in male fertility. In these genes, there has so far been limited research of single nucleotide variants and of copy number variants, but many structural variants are not visible using commonly used methods in clinical genetic testing. Therefore, apart from chromosome Y microdeletions and chromosomal numerical and structural anomalies, such as balanced translocations, the role of smaller structural variants in male infertility is unknown, but based from what we know from other diseases, they also may play a role in male infertility. Optical genome mapping is a novel method for the detection of structural variants, such as balanced and unbalanced translocations, insertions, duplications, deletions, and complex structural rearrangements in a wide range of sizes. By using optical genome mapping to test a cohort of 88 infertile men and 132 healthy controls, we aimed to provide the first insights into the range of SV that may be associated with MI. We found, by using optical genome mapping, the overall number of structural variants in MI patients not to be significantly different to the control group. However, by looking at genes and regions associated with MI, we can find rare structural variants that are absent from controls in 25.0% of MI patients. These variants include inversions, duplications, amplifications, deletions (e.g. deletion in SPAG1), and insertions/expansions (e.g. in DMPK), that were validated using additional methods. Five of these variants (5.6%) were likely causative, and two would be missed by traditional approaches. While the remaining SV cannot be currently classified as pathogenic according to existing criteria, they open a new avenue in genetic research of MI.

6
Associations Between Prenatal Cannabis Exposure and Birth Outcomes: Results from a Prospective Cohort Study

Constantino-Pettit, A.; Trammel, C.; Agrawal, A.; Smyser, C.; Carter, E.; Bogdan, R.; Rogers, C.

2026-03-03 obstetrics and gynecology 10.64898/2026.03.01.26347369
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ABSTRACT/SUMMARYO_ST_ABSObjectiveC_ST_ABSCannabis use during pregnancy is increasing; associations with neonatal growth may be confounded by nicotine. We evaluated prenatal cannabis exposure (PreCE) and neonatal outcomes in a prospective cohort with biochemical control for nicotine exposure. MethodsIn the Cannabis Use During Early Life and Development (CUDDEL) study, pregnant women with a lifetime history of cannabis use were classified as PreCE if they self-reported use or had urine THC-COOH positivity at any trimester (n=297) and as unexposed if they reported no use and tested negative (n=151). Linear regression and modified Poisson models estimated associations with birthweight and small for gestational age (SGA; <10th and <5th percentiles), adjusting for sociodemographic factors, gestational age, maternal age and BMI, and urinary cotinine. Analyses stratified by cannabis use frequency (>weekly vs <monthly) and cotinine status. ResultsParticipants (N=448; 18-41 years; 85.3% non-Hispanic Black) had lower birthweight with PreCE in adjusted models (Beta=-0.08; padj=0.041). High-frequency PreCE was associated with lower birthweight compared with unexposed pregnancies (Beta=-0.13; padj=0.03), whereas low-frequency PreCE was not. Cotinine-positive PreCE showed the greatest birthweight reduction versus unexposed (Beta=-0.20; padj<0.001). PreCE was also associated with higher likelihood of SGA <5th percentile; risk was highest in PreCE+Nicotine compared with both unexposed and PreCE-Nicotine groups. ConclusionsPrenatal cannabis exposure was associated with reduced birthweight and SGA in this cohort. Nicotine co-exposure intensified these associations, yet effects persisted without cotinine, supporting cannabis as an independent perinatal risk factor and emphasizing the value of cotinine assessment in populations where blunt use or secondhand exposure is common.

7
Quantitative Ultrasound Biomarkers of Testicular Spermatogenic Function

Kohn, T. P.; Coady, P. J.; Oppenheimer, A. G.; Walia, A.; Hernadez, B. S.; Kohn, J. R.; Parikh, N.; Bazzi, M.; Stocks, B.; Khera, M.; Lipshultz, L. I.

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IntroductionNon-obstructive azoospermia (NOA) represents the most severe form of male infertility. Current clinical tools have limited ability to predict sperm production or guide surgical sperm retrieval. Conventional B-mode ultrasound provides qualitative grayscale images and cannot characterize testicular microstructure relevant to spermatogenesis. Quantitative ultrasound (QUS) provides objective parameters from raw radiofrequency data, which quantitatively measure tissue heterogeneity. We hypothesize that men with spermatogenesis will have different QUS features compared to men without spermatogenesis (measured by total motile count, TMC, on semen analysis), with the goal of identifying imaging biomarkers for prognosis and intraoperative guidance. MethodsWe prospectively analyzed men presenting for infertility evaluation who underwent high-frequency ultrasound imaging and semen analysis. Imaging was performed using a 36-MHz transducer with fixed acquisition parameters. Ninety-two QUS features were extracted from manually annotated testicular regions of interest, including Nakagami distribution parameters (m, {omega}, k), envelope statistics, and texture features. Univariate associations between each QUS feature and TMC were assessed using Spearman correlation with Bonferroni correction. Top-performing features were evaluated using logistic regression and receiver operating characteristic (ROC) analysis to discriminate sperm presence or absence (TMC>0 vs TMC=0). ResultsThirty-seven men (18 azoospermic, 19 with sperm present in the ejaculate) contributed 135 regions of interest. Seventeen of 92 QUS features significantly correlated with TMC after correction. The coefficient of variation of the Nakagami k-factor within the superficial testicular parenchyma (K_Zone1_Cv) demonstrated the strongest correlation ({rho}=0.51, corrected p<0.001), suggesting that greater spatial heterogeneity in the superficial parenchyma was associated with higher sperm counts. K_Zone1_Cv discriminated sperm presence with an AUC of 0.77 (95% CI 0.60-0.92), sensitivity 73.7%, and specificity 83.3%. QUS features with the highest univariate association were highly intercorrelated, suggesting a shared biological signal. ConclusionQuantitative ultrasound-derived measures of testicular microstructure heterogeneity correlate with sperm production and demonstrate moderate discrimination of sperm presence. These findings suggest QUS may provide a non-invasive imaging biomarker of spermatogenesis. Study findings warrant further assessment and validation in male infertility for sperm retrieval prognosis and the potential for intra-operative surgical guidance.

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Temporal trends in preterm birth rate over the last 30 years in Sweden: a population-based study

Han, B.; Sundelin, H.; Ytterberg, K.; Juodakis, J.; Nyeboe, P.; Rosengren, A.; Stromberg, U.; Norman, M.; Svanvik, T.; Sole-Navais, P.; Jacobsson, B.

2026-02-26 obstetrics and gynecology 10.64898/2026.02.24.26346962
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ObjectivesTo determine temporal trends in the rates of preterm birth and its sub-types in Sweden and assess the contribution of known-risk factors. DesignA population-based register study. SettingSweden. Participants (Instead of patients or subjects)3,264,146 pregnancies registered in the Swedish Medical Birth Registry with information on pregnancy duration and onset of labour (1991 - 2021). Main outcome measuresThe primary outcomes were the overall, spontaneous and iatrogenic preterm birth rates between 1991 - 2021, stratified on singleton and multiple births, as well as for extremely preterm (<28 weeks, <196 days), very preterm (28-31 weeks, 196 - 224 days), moderately preterm (32 - 33 weeks, 224 - 238 days), and late preterm (34 - 36 weeks, 238 - 259 days) births. Using logistic regression models, we investigated whether maternal age at conception, use of artificial reproductive technologies, smoking, parity, and maternal continent of birth were associated with the observed trends. ResultsThe overall preterm birth rate was stable between 1991 - 2005 at 5.50% (95% CI: 5.37%, 5.63% in 1991) but decreased thereafter to 4.78% (95% CI: 4.66%, 4.91%) in 2021, a finding confined to spontaneous preterm births. The largest decline was observed in late preterm births, from 3.92% (95% CI: 3.80%, 4.05%) in 2005 to 3.52% (95% CI: 3.41%, 3.63%) in 2021. Moderately preterm birth also declined (0.70%, 95% CI: 0.65%, 0.76% in 2005 to 0.53%; 95% CI: 0.49%, 0.58% in 2021), whereas very-extremely preterm birth did not. Decreased spontaneous preterm birth rates were observed in women born in European, Asian and African countries, with largest decline observed in the latter (rate in 1991 = 2.65%, 95% CI: 1.74%, 3.86%; rate in 2021 = 1.72%, 95% CI: 1.42%, 2.07%). Adjusting for maternal and obstetric risk factors didnt alter these associations. ConclusionsWhile rates of preterm birth have been stable or increased globally, they have decreased in Sweden from 2006 - 2021, despite the lack of any nation-wide preventive strategy during this period. Understanding the reasons for this decline will provide useful strategies to make the decline a rule, rather than an exception.

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Vaginal Microbiome and Preterm Birth in Pregnant Indian Women

Singh, A.; Modi, D.; Chhabria, K.; Vashist, N.; Singh, S.; Suneja, G.; Hussein, A.; Das, G.; Choprai, S.; Urhekar, A.; Kumar, S.

2026-02-24 obstetrics and gynecology 10.64898/2026.02.19.26346663
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ObjectivePreterm birth (PTB) is a leading cause of neonatal morbidity and mortality worldwide, with India alone contributing nearly 27% of the global PTB burden. Although alterations in the vaginal microbiome have been implicated in PTB, its association in the Indian context is underexplored. This study aimed to investigate the association of vaginal microbiome and PTB in Indian women at the time of delivery. Study designThe vaginal swabs were collected at the time of delivery from 72 women (31 term, 41 preterm) admitted to a tertiary care hospital in Western India. Microbial DNA was extracted, and the V3-V4 region of the 16S rRNA gene was sequenced. Community composition, alpha and beta diversity, and differential taxonomic abundance were assessed using bioinformatics pipelines. ResultsAt the time of delivery, there were no significant differences in alpha or beta diversity between term and preterm groups. Principal coordinate and unsupervised clustering analyses showed no group-wise segregation. The relative abundance of individual Lactobacillus species, including L. iners and L. helveticus, did not differ significantly between the two groups. However, a modest difference in the relative abundance of Streptococcus was observed between the two groups after adjustment. ConclusionThis study found no major microbial shifts in the vaginal microbiome associated with preterm birth in this cross sectional cohort of Indian women, suggesting that vaginal dysbiosis at the time of delivery may not be a principal driver of PTB in this population. These findings underscore the need for larger, longitudinal, and ethnically diverse studies using standardized methodologies better to understand the microbiomes role in PTB risk.

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Maternal prenatal stress is associated with altered placental microstructure in low-risk pregnancies and pregnancies with Congenital Heart Disease

Bonthrone, A. F.; Cromb, D.; Ahmad Javed, S.; Aviles Verdera, J.; Pushparajah, K.; Rutherford, M.; Hutter, J.; Counsell, S. J.

2026-03-03 obstetrics and gynecology 10.64898/2026.03.02.26347408
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ObjectivesTo assess if maternal stress is higher in pregnancies with congenital heart disease (CHD) compared to low-risk pregnancies and if maternal stress is associated with placental microstructure and function. To explore if CHD alters the relationship between maternal stress and placental measures. MethodsIn this prospective observational study, 27 participants carrying a fetus with CHD and 42 participants with typical low-risk pregnancies underwent 1-2 combined diffusion{square}T2* relaxation placental MRIs from 20 weeks gestation (GA) and completed the Edinburgh Postnatal Depression Scale and State Trait Anxiety Inventory [43 male fetuses, median (IQR) GA at assessment 30.86 weeks (27.43-34.00), interval between assessments 6.00 weeks (4.86-7.14)]. 98 complete placental MRI and maternal stress datasets were available. Generalized Estimating Equations were used for analyses. ResultsHigher trait anxiety was associated with higher placental apparent diffusion coefficient (p=0.023) adjusting for CHD, sex, GA at assessment, GA at assessment2, state anxiety, depressive symptoms and previous mental health treatment. Maternal state anxiety (p=0.005) and depressive symptoms (p=0.046) were higher in pregnancies with CHD adjusting for GA at assessment and previous mental health treatment. CHD did not alter these relationships (p>0.119). ConclusionsMaternal proneness to anxiety, measured with the trait anxiety inventory, is associated with increased diffusivity in the placenta, which may reflect altered microstructural maturation. Mothers with fetal CHD show more depressive symptoms and feelings of anxiety and may benefit from screening for elevated maternal stress. The findings contribute to a growing body of research regarding the influence of prenatal stress on placental development. HighlightsO_LIMaternal stress and placental MRI data acquired in pregnancies with and without CHD C_LIO_LIMaternal trait anxiety is associated with increased placental diffusivity C_LIO_LIMaternal state anxiety and depressive symptoms are higher in fetal CHD C_LIO_LIState anxiety and depressive symptoms not associated with placental MRI measures C_LIO_LICHD did not moderate relationships between placental MRI measures and stress C_LI

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QUALITY OF LIFE AMONG INDIVIDUALS SEEKING FERTILITY TREATMENT IN UGANDA: FINDINGS FROM A CROSS-SECTIONAL FertiQoL SURVEY

Zaake, D.; Amongin, D.; Asefa, A.; Nakafeero, M.; Nalwadda, C. K.; Kayiira, A.; Kiwanuka, S. N.

2026-02-15 sexual and reproductive health 10.64898/2026.02.12.26346140
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BackgroundInfertility affects approximately one in six people globally and is associated with diminished quality of life (QoL). In Uganda, an estimated 6.4% of women experience infertility, yet evidence on fertility-specific QoL and its determinants remains limited. We assessed fertility-related QoL and associated factors among individuals seeking fertility care in public and private hospital settings in Kampala to inform patient-centred services. MethodologyWe conducted a hospital-based cross-sectional study (May 2024-January 2025) among 332 individuals aged 18-49 years attending fertility clinics at Kawempe National Referral Hospital (public; n=175) and St. Francis Hospital Nsambya (private; n=157). QoL was measured using the validated Core FertiQoL questionnaire, generating overall and domain scores (emotional, mind/body, relational, and social), transformed to a 0-100 scale (higher scores indicate better QoL). Mean scores were compared using independent-samples t-tests and one-way ANOVA. Multivariable linear regression identified factors independently associated with FertiQoL (=0.05). ResultsMost participants were female (87.1%) and [&le;]40 years (88.0%). Secondary infertility was reported by 50.3%, and 58.4% had infertility duration <5 years. The overall mean FertiQoL score was 61.9 (SD 14.7), with similar totals across hospitals. Mind/body scores were comparatively higher, while emotional scores were lowest (mean 54.3, SD 21.3). In adjusted analyses, male gender ({beta}=8.49; 95% CI 3.95-13.02; p<0.001) and secondary infertility ({beta}=7.45; 95% CI 4.41-10.49; p<0.001) were associated with higher FertiQoL scores. ConclusionsFertility-related QoL among patients seeking care in Kampala was moderate and did not differ by facility type. Gender and infertility type were key correlates, underscoring the need for integrated, gender-sensitive psychosocial support alongside clinical infertility care.

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A clinical decision making model for NTSV deliveries

Crabtree, L.; Frasch, M. G.; Gheorghe, C. P.

2026-03-02 obstetrics and gynecology 10.64898/2026.02.24.26346894
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ObjectiveTo evaluate modifiable antepartum and intrapartum factors associated with nulliparous, term, singleton, vertex (NTSV) cesarean delivery and to model risk stratified induction timing strategies that minimize cesarean risk across maternal risk profiles. Study DesignThis retrospective cohort study included all NTSV deliveries at a tertiary care center from January 2015 through August 2025 (overall cohort n=10,525; limited risk cohort n=5,663). Machine learning identified key predictors of cesarean delivery, with maternal age and pre pregnancy body mass index (BMI) used to define low, moderate, and high risk strata. Logistic regression estimated the association between induction and cesarean delivery, and a Monte Carlo simulation compared elective induction at 39, 40, or 41 weeks versus expectant management to 42 weeks within each stratum. ResultsCesarean delivery occurred in 20.1% of the overall cohort and 19.0% of the limited risk cohort, with a U shaped relationship between gestational age and cesarean risk and lowest rates at 38-39 weeks. Induction was associated with higher cesarean rates than spontaneous labor in both cohorts (overall: 24.1% vs. 17.1%; limited risk: 22.9% vs. 15.7%) after adjustment for age, BMI, and gestational age. No single induction policy minimized cesarean risk across all strata. For high risk patients (age >=35 years and BMI >=35), induction at 39 weeks yielded the lowest modeled cesarean rate, whereas later delivery (40 to 41 weeks or expectant management to 41 weeks) was favored for low and moderate risk patients. A universal 39 week induction policy for low and moderate risk strata modestly increased modeled cesarean rates, adding an estimated 46 cesarean deliveries. ConclusionGestational age at delivery and induction strategy are key modifiable determinants of NTSV cesarean delivery, but optimal timing varies by maternal age and BMI risk profile, supporting risk stratified rather than universal 39 week induction policies.

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Protocol for a prospective accuracy study on an artificial intelligence-based ultrasound system for gestational age estimation among pregnant women in Ghana, Kenya and South Africa

Swarray-Deen, A.; McDougall, A.; Chemway, R.; Craik, R.; Jayaratnam, S.; Joseph, N.; Mahar, R. K.; Koye, D. N.; Nguyen, L.; Simpson, J. A.; Gwako, G.; Hadebe, R.; Nartey, E. T.; Minckas, N.; Gulmezoglu, A. M.; Vogel, J. P.; Osman, A.; PEARLS Collaborators,

2026-02-15 obstetrics and gynecology 10.64898/2026.02.12.26346216
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BackgroundRisk screening for pre-eclampsia relies on accurate gestational age assessment, but routine access to ultrasound-based gestational dating remains challenging in many low- and middle-income countries (LMICs). As part of the formative work for the "Preventing pre-eclampsia: Evaluating AspiRin Low-dose regimens following risk Screening" (PEARLS) trial, we aim to validate and implement an Artificial Intelligence (AI)-based algorithm for estimation of gestational age, using blind sweeps done with a handheld ultrasound device. This study protocol outlines the accuracy cohort for AI-based gestational age estimation in participating facilities in Ghana, Kenya, and South Africa. MethodsThis multi-country prospective cohort study will recruit 969 pregnant women at 13 health facilities across Kenya, Ghana and South Africa. The eligible population are pregnant women presenting for antenatal visit from 11+0 to 13+6 weeks gestation. Eligible women will have a gestational age assessment by a trained sonographer using fetal biometry (reference standard), followed by gestational age estimation conducted by a trained midwife using the AI-based Intelligent Ultrasound ScanNav FetalCheck system (experimental). Both conventional and AI-based gestational age scans will be conducted with the General Electric (GE) VScanTM Air platform. Women will return for a second visit between 14+0 and 27+6 weeks gestation (week of visit is randomly selected) for an assessment with both conventional and AI-based ultrasound. The primary objective is to determine the accuracy and precision of gestational age estimation using an AI ultrasound system in first and second trimesters, as compared to gestational age estimation using crown-rump length (CRL) measurement by conventional ultrasound in first trimester (11+0 to 13+6 weeks). DiscussionThe study will provide critical evidence on the accuracy of a point-of-care, AI-based gestational age estimation ultrasound algorithm in sub-Saharan African settings. This study will inform the design of the PEARLS trial, as well as provide vital evidence for expanding implementation of ultrasound-based gestational age assessment for women in Africa.

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Retrospective Validation Of a Patient-Initiated Preconception Screener Against Obstetric Comorbidity Indices To Assess Pregnancy Complications

Khan, U.; Shah, S.; Luna-Victoria, G.; Groves, L.; Ramos, D.; Sirota, M.; Oskotsky, T.

2026-03-03 obstetrics and gynecology 10.64898/2026.03.02.26347437
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ObjectiveTo retrospectively validate an electronic health record (EHR) implementation of the patient-initiated PreMA screener and compare its association with severe maternal morbidity (SMM) outcomes against established obstetric comorbidity indices. MethodsWe conducted a retrospective observational study using UCSF (single center) and UC-wide (multi-center) de-identified EHR data, identifying live-birth deliveries with documented preconception data. PreMA and established comorbidity index (Bateman and Leonard) scores were computed from preconception diagnoses, standardized to z-scores, and modeled as continuous predictors of SMM and non-transfusion SMM (NT-SMM) using logistic and Poisson regression models, with stratified analyses by race, ethnicity, and neighborhood deprivation. To examine the relationship between individual PreMA questionnaire domains and outcomes, we used adjusted Poisson regression to estimate the association of each domain with SMM and NT-SMM. ResultsAcross both cohorts, higher standardized PreMA, Bateman, and Leonard scores were consistently significantly associated with increased risk of SMM and NT-SMM, with relative risk estimates generally in the [~]1.2-1.4 range per standard deviation (adj. p < 0.001), and similar magnitude across indices and cohorts. Significant associations persisted across racial, ethnic, and socioeconomic, and item-level analyses suggested heterogeneity across PreMA domains, with cardiovascular domains showing the strongest adjusted associations. ConclusionAn EHR-derived PreMA score demonstrated robust, generalizable associations with severe maternal morbidity outcomes comparable to established clinician-facing indices, supporting PreMAs validity as a scalable, patient-centered preconception risk assessment tool.

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Impact of Preterm Premature Rupture of Membranes on Composite Adverse Perinatal Outcomes and Associated Predictors Among Pregnant Women in Tigray, Northern Ethiopia: A Prospective Cohort Study

Welesamuel, G. T.; Araya, A.; Nega, G.; Alem, B.; Guesh, T.; Mekonene, H.; Abadi, F.; Gebreluel, H.; Asres, N.; Haile, T. G.; Alemayoh, T. T.

2026-02-24 obstetrics and gynecology 10.64898/2026.02.22.26346847
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BackgroundPreterm premature rupture of membranes (PPROM) is a leading contributor of adverse perinatal outcomes, particularly in low-resource and conflict-affected settings. Despite its clinical importance, prospective evidence on its impact on composite adverse perinatal outcomes in northern Ethiopia remains limited. This study examined the impact of Preterm premature rupture of membranes on composite adverse perinatal outcomes and identified associated predictors among pregnant women in public hospitals of Tigray, Northern Ethiopia. MethodsA hospital-based prospective cohort study was conducted among 578 singleton pregnancies (288 with Preterm premature rupture of membranes and 290 without it at [&ge;]28 weeks of gestation. Participants were followed from admission to delivery and to the early neonatal period. The primary outcome was a Composite adverse perinatal outcome, and the main exposure variable was Preterm premature rupture of membranes (PPROM). Modified Poisson regression with robust variance estimation was used to estimate adjusted relative risks (ARRs) with 95% confidence intervals (CIs) and a significant level was declared at p<0.05. ResultsOverall, 33.4% of neonates experienced at least one composite adverse perinatal outcome. The incidence was substantially higher among the PPROM group compared with the non-PPROM group (59.4% vs. 7.6%). After adjustment, PPROM was strongly associated with composite adverse perinatal outcomes (ARR = 7.22, 95% CI: 4.73-11.03). Independent predictors included previous pregnancy-related infection (ARR = 1.54; 95% CI: 1.08-2.22), absence of iron-folate supplementation during pregnancy (ARR=1.63; 95% CI: 1.153-2.29), pelvic pain (ARR = 2.09; 95% CI: 1.05-4.15), and latency period of 1-3 days (ARR = 1.41; 95% CI: 1.10-1.81) compared to <24 hours. Induced labor was protective (ARR=0.58; 95% CI: 0 .422-0.800). ConclusionPPROM markedly increases the risk of composite adverse perinatal outcomes in this post-conflict, resource-constrained setting. The first 72 hours following membrane rupture represent a particularly vulnerable period. Strengthening antenatal care, nutritional supplementation, infection prevention, and timely obstetric intervention could reduce preventable neonatal morbidity and mortality in similar contexts.

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Development and cross-tissue validation of a methylation profile score for the cortisol response to stress

Balfour, D.; Mittinty, M.; Nguyen, D. P.; Cohen-Woods, S.

2026-02-18 genetic and genomic medicine 10.64898/2026.02.17.26346504
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Hypothalamic-pituitary-adrenal axis (HPA axis) dysregulation is a risk factor for poor mental and physical health. Animal studies indicate that DNA methylation may be one mechanism through which stress can influence the function of the HPA axis, however human studies have not identified consistent individual loci. Machine learning can be used to develop methylation profile scores (MPSs), but this method has not yet been applied to HPA axis function. Using a novel machine learning pipeline, we developed an MPS to predict the salivary cortisol response (AUCi) to the Trier Social Stress Test (TSST) from whole blood Illumina Infinium HumanMethylation 450K BeadChip data (N = 84, mean age = 34, 49% female). The MPS was associated with the cortisol response in an independent, cross-tissue cohort (N = 53, mean age = 20, 51% female), both before ({beta} = 0.33, 95% CI [0.09, 0.54]) and after a social stressor ({beta} = 0.3, 95% CI [0.09, 0.47]). Functional characterisation revealed several immune, stress, and disease-related pathways and genes, including tolerance induction to self antigen, chronic myeloid leukemia, NR3C2, and PSMB4 (putatively causal in depression). We have developed and validated a novel epigenetic biomarker for stress reactivity, identifying a set of genomic loci where DNA methylation is associated with the cortisol response. Future research could investigate if HPA axis-related MPSs could be used alongside traditional risk factors to improve clinical risk assessment.

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Data Driven Endocrine Metabolic Phenotypes in Young Women With Polycystic Ovary Syndrome and Associations With Cardiometabolic Risk Markers

Piorkowska, N. J.; Nicifur, K.; Lesniewski, M.; Franik, G.; Bizon, A.

2026-03-03 endocrinology 10.64898/2026.02.25.26346893
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ContextPolycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder associated with reproductive dysfunction and long-term cardiometabolic risk. Traditional phenotype classifications based on diagnostic criteria may not fully capture the multidimensional biological variability underlying endocrine and metabolic risk profiles, particularly in young women. ObjectiveTo identify data-driven endocrine-metabolic phenotypes in young women with PCOS and evaluate their association with established cardiometabolic risk markers. Design and SettingCross-sectional study conducted at a tertiary Gynecological Endocrinology Clinic in Poland between January 2018 and May 2025. ParticipantsA total of 1300 young women diagnosed with PCOS according to Rotterdam criteria were included. The primary analytic cohort comprised 1032 participants aged 16-25 years with complete endocrine-metabolic biomarker data. Main Outcome MeasuresEndocrine-metabolic phenotypes were derived using principal component analysis followed by Gaussian mixture model clustering. Cardiometabolic risk endpoints included impaired glucose tolerance (2-hour plasma glucose during an oral glucose tolerance test [&ge;]140 mg/dL), an atherogenic lipid profile (triglycerides (TG)/high-density lipoproteins (HDL-C) ratio >3.50), elevated non-HDL cholesterol ([&ge;]130 mg/dL), and a composite outcome of any abnormality. ResultsPrincipal component analysis retained 10 components explaining 81.9% of total variance. Unsupervised clustering identified two stable phenotypes (silhouette = 0.392; ARI = 0.842). Cluster 0 (n=954; 92.4%) represented a mixed endocrine-metabolic profile, whereas cluster 1 (n=78; 7.6%) was enriched for thyroid/autoimmune features, with higher anti-thyroid peroxidase antibody levels and higher thyroid-stimulating hormone. Cluster 1 showed a higher prevalence of an atherogenic lipid profile compared with cluster 0, while differences in glucose intolerance and non-HDL cholesterol were modest. Logistic regression analyses suggested phenotype-specific variation in cardiometabolic risk markers. ConclusionsIn a large cohort of young women with PCOS, data-driven analysis identified two reproducible endocrine-metabolic phenotypes, including a distinct thyroid/autoimmune-enriched subgroup. These findings highlight clinically relevant heterogeneity beyond traditional diagnostic phenotypes and support the potential value of integrated endocrine-metabolic profiling for early risk stratification in PCOS.

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Maternal Willingness to Participate in Research Involving Neuroimaging, Biological Sample Collection, and Data Storage: Towards a Multicentre Neurodevelopmental Research in a low-resource setting

Piersson, A. D.; Amartey, C.; Quartei, S. T.; Dzefi-Tettey, K.; Sefogah, P. E.; Lopez, A. R.

2026-02-24 obstetrics and gynecology 10.64898/2026.02.22.26346849
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BackgroundMaternal participation in neurodevelopmental research involving neuroimaging and diverse biological samples is essential for understanding prenatal influences on early brain development, yet willingness in low-resource settings remains underexplored. MethodWe surveyed 300 mothers using a structured questionnaire to assess willingness to undergo brain health testing (with a focus on electroencephalography [EEG] and brain magnetic resonance imaging [MRI]), provide biological samples (blood, stool, urine, breast milk, placenta, amniotic fluid, vaginal/nasal fluid, saliva, tears), and consent to 10-year storage. Responses were analysed to examine associations between maternal sociodemographic factors and willingness to consent for each research component. ResultsNinety-two percent of participants expressed willingness for brain health testing, including [~]82% and [~]88% interest in EEG and MRI, respectively, even for untreatable conditions. Self-reported histories of foetal defects (5.3%) and birth defects (7.3%) were notably low. Biospecimen acceptance was highest (>95%) for routine samples (blood, stool, urine) but significantly low for sensitive specimens (breast milk, placenta, amniotic fluid: 51-55%) including (vaginal fluid, saliva, tears: 16-47%). Higher levels of maternal education consistently predicted consent across modalities, while being in a relationship increased willingness for stool, urine, placenta, amniotic fluid, MRI, and EEG. Low income reduced uptake for placenta, amniotic fluid, MRI, and EEG. Only 48% consented to 10-year storage of images and samples for future research. ConclusionThis study demonstrates high maternal willingness for neurodevelopmental research involving brain health testing and routine biospecimens in a low-resource setting. The findings highlight the feasibility of such protocols in a low-resource setting while exposing persistent inequities that risk underrepresenting disadvantaged mothers in maternal-child brain research. Contextually tailored consent models and capacity-building initiatives will be essential to ensure equitable, sustainable engagement across diverse LMIC populations.

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Variant curation of the largest compendium of FOXL2 coding and non-coding sequence and structural variants in BPES

Matton, C.; Van De Velde, J.; De Bruyne, M.; Van De Sompele, S.; Hooghe, S.; Syryn, H.; Bauwens, M.; D'haene, E.; Dheedene, A.; Cools, M.; Komatsuzaki, S.; Preizner-Rzucidlo, E.; Ross, A.; Armstrong, C.; Watkins, W.; Shelling, A.; Vincent, A. L.; Cassiman, C.; Vermeer, S.; Bunyan, D. J.; Verdin, H.; De Baere, E.

2026-03-02 genetic and genomic medicine 10.64898/2026.02.24.25339471
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Heterozygous FOXL2 (non-)coding sequence and structural variants (SVs) lead to blepharophimosis, ptosis and epicanthus inversus syndrome (BPES), a rare, autosomal dominant developmental disorder characterized by a completely penetrant eyelid malformation and incompletely penetrant primary ovarian insufficiency (POI). We collected variants from our in-house database, generated via clinical genetic testing and downstream research testing in the Center for Medical Genetics Ghent, Belgium (2001-2024), and via literature and other resources in the same period. All retrieved variants were categorized using ACMG/AMP classifications to increase the knowledge of pathogenicity. We collected 413 unique genetic defects of the FOXL2 region, including 76 novel variants, in 864 index patients. Of these, 87% of patients were identified with a coding FOXL2 sequence variant. The polyalanine tract is a known mutational hotspot of FOXL2, illustrated here by the high percentage of pathogenic polyalanine expansions (24%). Furthermore, the molecular spectrum in typical BPES index patients is characterized by 8% coding deletions and 3% deletions located up- and downstream of FOXL2. The remaining 2% carry translocations along with chromosomal rearrangements of 3q23. This uniform and structured reclassification, incorporating the largest dataset of variants implicated in FOXL2-associated disease so far, will improve both the diagnosis as well as genetic counselling for individuals with BPES.

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Evaluating Mid-Upper Arm Circumference Cut-Offs as a Screening Tool for Undernutrition in Pregnant Women: An Alternative to Body Mass Index

Sabed, S.; Sharmin, I.; Al Fidah, M. F.; Khan, A.-R.; Farzana, F. D.; Mahfuz, M. T.; Ara, G.; Hossain, M. S.; Ahmed, T.; Mahfuz, M.

2026-02-27 obstetrics and gynecology 10.64898/2026.02.25.26347073
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BackgroundUndernutrition during pregnancy is a major public health issue and may lead to negative pregnancy outcomes. The body mass index (BMI), considered widely used as the reference method for assessing nutritional status due to its established population-based cut-off points; however, it can be misleading in pregnancy. This study aimed to validate the mid-upper arm circumference (MUAC) as a screening tool for identifying undernourished pregnant women (PW) in an urban slum, compared to BMI. MethodsData for this analysis were extracted from studies conducted in Bauniabadh, a slum located in Dhaka, Bangladesh. The final sample size was 375 PW aged 15-39 years with a gestational age of <14 weeks. The first recorded weight during enrolment was considered a proxy for pre-pregnancy weight. Participants were classified as undernourished or well-nourished accordingly. The BMI Z-scores for adolescents and the BMI categories for adult women were used to define undernutrition. Receiver operating characteristic (ROC) curve analysis was used to calculate the area under the curve (AUC), sensitivity, specificity, predictive values, and likelihood ratios. BMI-MUAC concordance was analyzed using McNemars test to determine optimal MUAC cut-offs. ResultsAmong the candidate MUAC cut-off values, a threshold of <22.5 cm demonstrated high diagnostic accuracy, with 78.1% sensitivity, 92.9% specificity, an AUC of 85.5%, and a positive likelihood ratio (LR+) of 11.0. The alternative threshold of <23.0 cm showed higher sensitivity (84.4%) and AUC (86.9%) but lower specificity (89.4%) and LR+ (7.9). The difference in AUCs between the two thresholds was not statistically significant (p = 0.400). Using the <22.5 cm cut-off, 19.2% of pregnant women were classified as undernourished compared with 17.1% based on BMI. Concordance between MUAC <22.5 cm and BMI-defined undernutrition was satisfactory (p=0.182). ConclusionsMUAC can be considered a simple and effective screening tool for identifying undernutrition in PW. Given its strong diagnostic accuracy, a threshold of <22.5 cm may be a practical alternative to BMI and considered for integration into nutritional programs for PW in Bangladesh.