BACKGROUND: The existing evidence on the association between interpregnancy interval (IPI) and pregnancy outcomes primarily focuses on singleton pregnancies, with limited research on twin pregnancies.
OBJECTIVE: This study aimed to investigate the association between IPI and adverse perinatal outcomes in twin pregnancies.
METHODS: This population-based, retrospective cohort study analyzed data from the National Center for Health Statistics (NCHS) in the United States between 2016 and 2020. We included multiparous women aged 18 to 45 years with live-born twins without congenital anomalies, born between 26 and 42 weeks of gestation. Poisson regression models, adjusted for potential confounders, were used to evaluate the associations between IPI and adverse outcomes, including preterm birth (PTB) < 36 weeks, small for gestational age (SGA), neonatal intensive care unit (NICU) admission, neonatal composite morbidity and infant death. Missing data on covariates were managed using multiple imputation. Dose-response analyses were performed using the restricted cubic spines (RCS) approach. Subgroup analyses were stratified by maternal age, parity and combination of neonatal sex. Sensitivity analyses were conducted using complete data and excluding pregnancies with intervening events during the IPI.
RESULTS: A total of 143,014 twin pregnancies were included in the analysis. Compared to the referent group (IPI of 18-23 months), an IPI of less than 6 months was associated with an increased risk of PTB < 36 weeks (RR, 1.21; 95% CI: 1.17-1.25), SGA (RR, 1.11; 95% CI: 1.03-1.18), neonatal composite morbidity (RR, 1.19; 95% CI: 1.12-1.27), NICU admission (RR, 1.18; 95% CI: 1.14-1.22), and infant death (RR, 1.29; 95% CI: 1.05-1.60). An IPI of 5 years or more was associated with an increased risk of PTB < 36 weeks (RR, 1.18; 95% CI: 1.15-1.21), SGA (RR, 1.24; 95% CI: 1.18-1.30), neonatal composite morbidity (RR, 1.10; 95% CI: 1.05-1.15), and NICU admission (RR, 1.14; 95% CI: 1.11-1.17). The dose-response analyses showed that these outcomes had U-shaped or J-shaped associations with IPI. The associations between IPI and the outcomes slightly differed by advanced maternal age, parity and combination of neonatal sex. The sensitivity analyses yielded similar results to the main findings.
CONCLUSIONS: Extreme IPI, less than 6 months or more than 5 years, was associated with adverse outcomes in twin pregnancies. IPI could be used as a predictor for risk stratification in high-risk twin pregnancies.

OBJECTIVE: To investigate the contribution of longitudinal mean arterial pressure (MAP) measurement during the first, second, and third trimesters of twin pregnancies to the prediction of pre-eclampsia.
METHODS: A retrospective cohort study was conducted on women with twin pregnancies. Historical data between 2019 and 2021 were analyzed, including maternal characteristics and mean artery pressure measurements were obtained at 11-13, 22-24, and 28-33 weeks of gestation. The outcome measures included pre-eclampsia with delivery <34 and ≥34 weeks of gestation. Models were developed using logistic regression, and predictive performance was evaluated using the area under the curve, detection rate at a given false-positive rate of 10%, and calibration plots. Internal validation was conducted via bootstrapping.
RESULTS: A total of 943 twin pregnancies, including 36 (3.82%) women who experienced early-onset pre-eclampsia and 93 (9.86%) who developed late-onset pre-eclampsia, were included in this study. To forecast pre-eclampsia during the third trimester, the most accurate prediction for early-onset pre-eclampsia resulted from a combination of maternal factors and MAP measured during this trimester. The optimal predictive model for late-onset pre-eclampsia includes maternal factors and MAP data collected during the second and third trimesters. The areas under the curve were 0.937 (95% confidence interval [CI] 0.894-0.981) and 0.887 (95% CI 0.852-0.921), respectively. The corresponding detection rates were 83.33% (95% CI 66.53%-93.04%) for early-onset pre-eclampsia and 68.82% (95% CI 58.26%-77.80%) for late-onset pre-eclampsia.
CONCLUSIONS: Repeated measurements of MAP during pregnancy significantly improved the accuracy of late-onset pre-eclampsia prediction in twin pregnancies. The integration of longitudinal data into pre-eclampsia screening may be an effective and valuable strategy.

BACKGROUND: Geroscience focuses on interventions to mitigate molecular changes associated with aging. Lifestyle modifications, medications, and social factors influence the aging process, yet the complex molecular mechanisms require an in-depth exploration of the epigenetic landscape. The specific epigenetic clock and predictor effects of a vegan diet, compared to an omnivorous diet, remain underexplored despite potential impacts on aging-related outcomes.
METHODS: This study examined the impact of an entirely plant-based or healthy omnivorous diet over 8 weeks on blood DNA methylation in paired twins. Various measures of epigenetic age acceleration (PC GrimAge, PC PhenoAge, DunedinPACE) were assessed, along with system-specific effects (Inflammation, Heart, Hormone, Liver, and Metabolic). Methylation surrogates of clinical, metabolite, and protein markers were analyzed to observe diet-specific shifts.
RESULTS: Distinct responses were observed, with the vegan cohort exhibiting significant decreases in overall epigenetic age acceleration, aligning with anti-aging effects of plant-based diets. Diet-specific shifts were noted in the analysis of methylation surrogates, demonstrating the influence of diet on complex trait prediction through DNA methylation markers. An epigenome-wide analysis revealed differentially methylated loci specific to each diet, providing insights into the affected pathways.
CONCLUSIONS: This study suggests that a short-term vegan diet is associated with epigenetic age benefits and reduced calorie intake. The use of epigenetic biomarker proxies (EBPs) highlights their potential for assessing dietary impacts and facilitating personalized nutrition strategies for healthy aging. Future research should explore the long-term effects of vegan diets on epigenetic health and overall well-being, considering the importance of proper nutrient supplementation.
BACKGROUND: Clinicaltrials.gov identifier: NCT05297825.

Twin births are related with maternal and fetal adverse outcomes. Little was known about the comparability of the cognitive, behavioral development and brain structure between twins and singletons in early adolescence. This retrospective cohort study was based on data from the United States population-based, prospective, longitudinal observational Adolescent Brain Cognitive Development study. Children with complete twin status information were enrolled, and the exposure variable was twin status. Primary outcomes were cognitive, behavioral development and brain structure in early adolescence. Cognitive and behavioral outcomes were assessed by using the NIH Toolbox and Child Behavioral Checklist, respectively. Brain structure was evaluated by the cortical thickness, area, and volume extracted from the magnetic resonance imaging (MRI) data. Subgroup analyses were conducted by prematurity, birth weight, with sibling, genetic profiles, and twin types (zygosity). From 1st September 2016 to 15th November 2018, 11545 children (9477 singletons and 2068 twins) aged 9-10 years were enrolled. Twins showed mildly lower cognitive performance (|t|> 5.104, P-values < 0.001, False Discovery Rate [FDR] < 0.001), better behavioral outcome (|t|> 2.441, P-values < 0.015, FDR < 0.042), such as lower scores for multiple psychiatric disorders and behavioral issues, and smaller cortical volume (t = - 3.854, P-values < 0.001, FDR < 0.001) and cortical area (t = - 3.872, P-values < 0.001, FDR < 0.001). The observed differences still held when stratified for prematurity, birth weight, presence of siblings, genetic profiles, and twin types (zygosity). Furthermore, analyses on the two-year follow-up data showed consistent results with baseline data. Twin status is associated with lower cognitive and better behavioral development in early adolescence accompanied by altered brain structure. Clinicians should be aware of the possible difference when generalizing results from adolescent twin samples to singletons.

BACKGROUND: Strategies of prevention for psychiatric disorders need a deep understanding of the aetiological factors involved in the psychopathological processes. Our twin study aims at disentangling the contributions of genes and environment to schizotypal and hypomanic dimensions, considering the role of stressful life events (LEs) and the quality of family relationships.
METHODS: The Magical Ideation Scale (MIS) and Perceptual Aberration Scale (PAS) were used to assess positive schizotypy, while Hypomanic Personality Scale (HPS) and its sub-scales were used to investigate proneness to affective disorders. 268 twins (54.5 % female; aged 18.0 ± 6.68) were included. Participants filled out a questionnaire on LEs and their parents provided an evaluation of intra-family relationship (Relationship Quality Index, RQI). Classic univariate twin models for quantitative traits were fitted for scales, and the effects of covariates (LEs and RQI) were assessed.
RESULTS: For MIS, HPS and its sub-scales, significant common and unique environmental effects were detected, with genetic factors affecting only HPS Social Vitality sub-scale. Unique environment was the only source of variance of PAS score. The number of recent LEs influenced MIS and PAS models, while RQI score affected MIS model.
CONCLUSIONS: The main limitation of the study is the small sample size, which reduces statistical power and may potentially lead to an underestimation of heritability. Additionally, the cross-sectional design limits the possibility to draw causal considerations.
CONCLUSIONS: Findings provide preliminary evidence for a significant environmental role in modulating states of vulnerability. Moreover, the expression of positive schizotypy resulted influenced by recent stressors and intra-family relationships.

OBJECTIVE: To investigate the risk factors for bronchopulmonary dysplasia (BPD) in twin preterm infants with a gestational age of <34 weeks, and to provide a basis for early identification of BPD in twin preterm infants in clinical practice.
METHODS: A retrospective analysis was performed for the twin preterm infants with a gestational age of <34 weeks who were admitted to 22 hospitals nationwide from January 2018 to December 2020. According to their conditions, they were divided into group A (both twins had BPD), group B (only one twin had BPD), and group C (neither twin had BPD). The risk factors for BPD in twin preterm infants were analyzed. Further analysis was conducted on group B to investigate the postnatal risk factors for BPD within twins.
RESULTS: A total of 904 pairs of twins with a gestational age of <34 weeks were included in this study. The multivariate logistic regression analysis showed that compared with group C, birth weight discordance of >25% between the twins was an independent risk factor for BPD in one of the twins (OR=3.370, 95%CI: 1.500-7.568, P<0.05), and high gestational age at birth was a protective factor against BPD (P<0.05). The conditional logistic regression analysis of group B showed that small-for-gestational-age (SGA) birth was an independent risk factor for BPD in individual twins (OR=5.017, 95%CI: 1.040-24.190, P<0.05).
CONCLUSIONS: The development of BPD in twin preterm infants is associated with gestational age, birth weight discordance between the twins, and SGA birth.
目的: 分析胎龄<34周双胎早产儿发生支气管肺发育不良（bronchopulmonary dysplasia, BPD）的危险因素，为临床早期识别双胎早产儿BPD的发生提供依据。方法: 回顾性收集全国22家医院2018年1月—2020年12月收治的胎龄<34周双胎早产儿，根据双胎儿患病情况分为三组：两胎均为BPD组、仅一胎为BPD组、两胎均非BPD组，分析双胎早产儿发生BPD的危险因素；并对仅一胎为BPD组患儿进一步分析，组内配对分析双胎早产儿发生BPD的产后危险因素。结果: 共纳入胎龄<34周的双胎儿共904对。多因素logistic回归分析中，与两胎均非BPD组相比，双胎出生体重差异>25%是双胎中仅一胎患BPD的危险因素 （OR=3.370，95%CI：1.500~7.568，P<0.05），胎龄大是双胎均患BPD的保护因素（P<0.05）。对双胎中仅一胎为BPD组进行组内条件logistic回归分析，提示小于胎龄儿是双胎内个体发生BPD的危险因素（OR=5.017，95%CI：1.040~24.190，P<0.05）。结论: 双胎早产儿BPD的发生不仅与胎龄相关，也与双胎出生体重差异、小于胎龄儿密切相关。.

UNASSIGNED: The association between perceived stress (PS) and gaming addiction (GA) is well documented. However, the mechanism for explaining this association remains unclear. Using a genetically informative design, this study aims to distinguish between the diathesis-stress and bio-ecological models of gene by environment interaction (G x E) to explain the underlying mechanism of the relationship.
UNASSIGNED: In total, 1,468 twins (mean age = 22.6 ± 2.8 years) completed an online survey including the GA and PS scales. Twin correlations for GA and PS were computed and univariate model-fitting analysis was conducted to determine genetic and environmental influences on GA and PS. The bivariate G x E model-fitting analysis was performed to determine the best G x E interaction model.
UNASSIGNED: Additive genetic, shared environmental, and non-shared environmental effects were 0.70 (95%CI = 0.61, 0.77), 0.00, and 0.30 (95%CI = 0.26, 0.33), and 0.38 (95%CI = 0.24, 0.55), 0.35 (95% CI = 0.18, 0.51), and 0.22 (95%CI = 0.20, 0.26) for GA and PS, respectively. Bivariate G x E model-fitting analysis supported the diathesis-stress model, where genetic influences on GA were greater in higher levels of PS, whereas environmental influences on GA were small and constant across levels of PS.
UNASSIGNED: The evidence for the diathesis-stress model for GA is consistent with the etiological process of many forms of psychopathology. The findings should be incorporated in clinical settings to improve the treatment of GA, and used in developments of intervention and prevention methods for GA.

OBJECTIVE: High levels of physical activity have been documented in eating disorder patients. Our aim was to examine whether adolescent leisure-time physical activity is prospectively associated with eating disorders in adolescence and young adulthood.
METHODS: Finnish twins born in 1983-1987 reported their physical activity frequency at ages 12, 14, and 17. A subsample of participants underwent structured, retrospective interviews for eating disorders at the mean age of 22.4 years. Associations between female twins\' physical activity and future eating disorders (571-683 twins/wave) were investigated with the Cox proportional hazards model. To illustrate the physical activity similarity of the co-twins in a twin pair, we used cross-tabulation of eating disorder-discordant twin pairs (13-24 pairs/wave).
RESULTS: After adjusting for several covariates, we found no statistically significant longitudinal association between physical activity and eating disorders. This applied when all eating disorders were combined but also when assessed separately as restrictive and non-restrictive eating disorders. Co-twins\' physical activity in adolescence tended to be similar irrespective of their future eating disorder, supporting the results of the regression analysis.
CONCLUSIONS: We observed no evidence of adolescent physical activity frequency being prospectively associated with eating disorders in female twins. Further longitudinal studies with larger sample sizes and more detailed physical activity data are needed.
METHODS: III, evidence obtained from cohort or case-control analytic studies.

UNASSIGNED: Twin studies have demonstrated that posttraumatic stress disorder (PTSD) is moderately heritable, and the pattern of findings across studies suggests higher heritability in females compared with males. Formal testing of sex differences has yet to be done in twin studies of PTSD. The authors sought to estimate the genetic and environmental contributions to PTSD, and to formally test for sex differences, in the largest sample to date of both sexes, among twins and siblings.
UNASSIGNED: Using the Swedish National Registries, the authors performed structural equation modeling to decompose genetic and environmental variance for PTSD and to formally test for quantitative and qualitative sex differences in twins (16,242 pairs) and in full siblings within 2 years of age of each other (376,093 pairs), using diagnostic codes from medical registries.
UNASSIGNED: The best-fit model suggested that additive genetic and unique environmental effects contributed to PTSD. Evidence for a quantitative sex effect was found, such that heritability was significantly greater in females (35.4%) than males (28.6%). Evidence of a qualitative sex effect was found, such that the genetic correlation was high but less than complete (rg=0.81, 95% CI=0.73-0.89). No evidence of shared environment or special twin environment was found.
UNASSIGNED: This is the first demonstration of quantitative and qualitative sex effects for PTSD. The results suggest that unique environmental effects, but not the shared environment, contributed to PTSD and that genetic influences for the disorder are stronger in females compared with males. Although the heritability is highly correlated, it is not at unity between the sexes.

OBJECTIVE: To develop a prediction model for hypertensive disorders in pregnancy (HDP) and gestational diabetes (GDM) in twin pregnancies utilizing characteristics at the prenatal care entry level.
METHODS: Cross-sectional study using the US national live birth data between 2016 and 2021. The association of all prenatal candidate variables with HDP and GDM was tested with uni- and multi-variable logistic regression analyses. Prediction models were built with generalized linear models using the logit link function and classification and regression tree approach (XGboost) machine learning (ML) algorithm. Performance was assessed with repeated 2-fold cross-validation and performance metrics we considered were area under the curve (AUC). P value <0.001 was considered statistically significant.
RESULTS: A total of 707,198 twin pregnancies were included in the HDP analysis and 723,882 twin pregnancies for the GDM analysis. The incidence of HDP and GDM significantly increased from 12.2% in 2016 to 15.4% in 2021 and from 8.1% in 2016 to 10.7% in 2021, respectively. Factors that increase the risk of HDP in twin gestations are maternal age <20, age≥35, infertility, prepregnancy DM, non-Hispanic Black population, obesity, and those with Medicaid insurance (p<0.001). Factors that more than doubled the risk are obesity class II and III (p<0.001). Factors that increase the risk of GDM in twin gestations are age <25, age≥30, history of infertility, prepregnancy hypertension, non-Hispanic Asian population, non-US nativity, and obesity (p<0.001). Factors that more than doubled the risk are maternal age ≥ 30 years, non-Hispanic Asian, and class I, II, and III maternal obesity ( p<0.001). For both HDP and GDM, the performance of the ML and logistic regression model was mostly similar with negligible difference in terms of all tested performance domains. The AUC of the final ML model for HDP and GDM were 0.62±0.004, and 0.67±0.004, respectively.
CONCLUSIONS: The incidence of HDP and GDM in twin gestations is increasing. The predictive accuracy of the machine learning model for both HDP and GDM in twin gestations is similar to that of the logistic regression model. Both models had modest performance, well-calibrated, and neither had a poor fit. This article is protected by copyright. All rights reserved.