Fetuses undergo major surgical stress as well as fluid shifts secondary to both twin-twin transfusion (TTTS) as well as the fetoscopic surgery for treatment of TTTS. While the pathophysiology of TTTS is understood, the acute metabolic changes that fetuses experience from fetoscopic surgery are not. We sought to evaluate the changes in recipient metabolomic profile secondary to TTTS surgery. Amniotic fluid was collected at the beginning and end of four TTTS surgical cases performed from 12/2022-2/2023. Samples were immediately processed and evaluated via NMR-based Metabolomics Facility protocol. In univariate analysis, 12 metabolites (glucose, lactate, and 10 key amino acids) showed statistically significant changes between the beginning and end of the surgery. Among these, 11 metabolites decreased at the end, while only lactate increased. Supervised oPLS-DA modeling revealed pyruvate and lactate as the two metabolites most impact on the variance between cases, and that 40% of metabolomic changes could be attributed directly to the timing that the sample was taken (i.e., if pre- or postoperatively). These results indicate significant metabolic changes in the recipient twin during fetoscopic surgery for TTTS. These findings of decreased glucose, increased lactate, and decreased amnio acids would indicate increased catabolism during surgery. This study raises questions regarding optimal maternal and fetal nutrition during surgery and if nutritional status could be optimized to further improve twin survival during fetoscopic surgery.

Our knowledge of monochorionic pregnancies\' complications is largely based on the extensive ongoing research on monochorionic placental structure. Previous studies on the concordance of umbilical cord insertions are limited. This study aimed to evaluate placental anastomoses and cord insertions as independent risk factors for neonatal adverse outcomes.
This was a prospective study conducted at Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy from April 2021 to December 2022. Seventy-six women with a monochorionic pregnancy were enrolled at their first-trimester scan. After delivery, all placentas that were confirmed to be monochorionic were analyzed according to standard protocols, including those of complicated monochorionic twin pregnancies. The primary outcomes were a Composite Monochorionic Pregnancy Outcome (CMPO) and a Composite Neonatal Adverse Outcome (CNAO). The secondary outcome was the birth weight discordance between the neonates.
The CMPO occurred in 15.8 % pregnancies, and the CNAO occurred in 67.1 % pregnancies. The analysis confirmed a significant association between velamentous cord insertions and neonatal adverse events (p = 0.003). Also, a significant positive association (p = 0.0326) between twin birth weight discordance and discordance in twins umbilical cord insertions\' sites was found. No significant association between the number and type of the anastomoses and both the CMPO or CNAO was detected.
Our data suggest that the routine sonographic assessment of umbilical cords\' insertion sites during the first trimester could be helpful in predicting fetal and neonatal adverse events. We believe that this sonographic assessment should start to be implemented in our routine care of monochorionic pregnancies.

OBJECTIVE: To explore asymmetry values of antimeric deciduous tooth crown dimensions in three types of twins: monozygotic (MZ), dizygotic same-sex (DZ) and opposite-sex (OS) vs. single-born controls.
METHODS: Mesiodistal and labio-lingual crown dimensions of second deciduous molars and mesiodistal canine and first molar crown dimensions of 2159 children at 6-12 years of age were evaluated, originating from the US cross-sectional Collaborative Perinatal Study from the 1970s, including altogether MZ (n = 28), DZ same-sex (n = 33) and OS (n = 39) pairs. Single born (n = 1959) were used as controls.
METHODS: Dental casts were measured for comparison of variance relationships calculated from antimeric teeth, exhibiting fluctuating (FA), and directional (DA) asymmetry using anova.
RESULTS: Significant differences appeared in MZ and OS girls in DA of deciduous canines, which gain size in the first and second trimester, and deciduous second molars, which finally stop crown growth during the early post-natal period. Significantly, increased FA values appeared for lower deciduous canines and second molars, indicating greatest environmental stress in OS girls, MZ girls and DZ boys. Twin girls had more fluctuating and directional crown asymmetry than twin boys, but in some dimensions, the twins were more symmetric than controls.
CONCLUSIONS: Transmembrane hormonal influence between opposite-sex twins, and late gestational stress factors, caused by placental malfunction and/or monochorionicity, may be involved in asymmetric growth of antimers, during critical periods of crown size gain.

BACKGROUND: Monochorionic pregnancies are a significant part of the workload in diagnostic imaging, and must be assessed frequently for the detection of twin-twin transfusion syndrome. Recognizing placental dichotomy at the time of routine fetal cerebral artery Doppler screening is important for alerting the clinician to potential twin anemia polycythemia sequence, an important subset of feto-fetal transfusions.
METHODS: A 36-year-old multigravid woman with a twin pregnancy delivered at 33 weeks\' gestation after fetal distress was identified. Twin anemia polycythemia sequence was diagnosed after delivery. Regular prenatal ultrasound scans had not identified oligo- or polyhydramnios. Retrospective assessment of the ultrasound images of the placenta showed marked dichotomy, with the anemic twin\'s portion being hyperechogenic.
CONCLUSIONS: Identification of placental dichotomy, in addition to screening with cerebral Doppler flow studies, may lead to earlier identification of twin anemia polycythemia sequence and improved outcomes. 
Contexte : Les grossesses monochorioniques représentent une partie significative de la charge de travail en imagerie diagnostique et doivent fréquemment faire l’objet d’une évaluation aux fins de la détection du syndrome transfuseur-transfusé. Il est important de reconnaître la présence d’une dichotomie placentaire au cours de la tenue d’une étude Doppler régulière de l’artère cérébrale fœtale, et ce, de façon à pouvoir alerter le clinicien quant à la présence possible d’une séquence anémie polyglobulie gémellaire (un sous-ensemble important du syndrome transfuseur-transfusé). Cas : Une multigravide de 36 ans connaissant une grossesse gémellaire a accouché à 33 semaines de gestation, à la suite de l’identification d’une détresse fœtale. Une séquence anémie polyglobulie gémellaire a été diagnostiquée à la suite de l’accouchement. Les échographies prénatales régulières n’avaient pas détecté la présence d’un oligohydramnios ou d’un polyhydramnios. L’analyse rétrospective des images échographiques du placenta a mis au jour la présence d’une dichotomie marquée, la partie relevant du jumeau anémique y apparaissant comme étant hyperéchogène. Conclusion : L’identification de la dichotomie placentaire (s’ajoutant au dépistage au moyen d’études Doppler cérébrales) pourrait mener à l’identification précoce de la séquence anémie polyglobulie gémellaire et à l’amélioration des issues.