Comment on “Uncomplicated Monochorionic Twins: Neurodevelopmental Insights and Implications”

Monochorionic (MC) twins carry a higher risk of adverse outcomes than dichorionic twins or singleton gestations due to hemodynamic complications such as twin-twin transfusion syndrome, twin anemia-polycythemia sequence (TAPS), twin reversed arterial perfusion (TRAP) sequence, and selective fetal growth restriction (sFGR). Emerging evidence suggests that even uncomplicated MC twin pregnancies differ physiologically from singleton pregnancies, including an estimated 7% risk of neuromorbidity attributable to shared placental anatomy alone. Optimal rehabilitation for children with neurodevelopmental disorders is time-sensitive and relies on early-life neuroplasticity. The objective of this study is to evaluate neurodevelopmental outcomes through 3 years of age in children born from uncomplicated monochorionic diamniotic (MCDA) twin pregnancies. In this prospective observational cohort study, twins born from uncomplicated MCDA pregnancies at Buzzi Children’s Hospital in Milan, Italy, between 2015 and 2022 underwent postnatal neurodevelopmental follow-up. Pregnancies were included if delivery occurred spontaneously between 34 and 37 weeks’ gestation or through planned delivery between 36 and 37 weeks. Exclusion criteria included major congenital or structural anomalies, intrauterine fetal death, TTTS, TAPS, TRAP sequence, or sFGR. The primary objective was to assess neurodevelopmental outcomes at 12, 24, and 36 months of age, and the secondary objective was to develop a structured follow-up protocol for these patients. Neurological and behavioral outcomes were evaluated and categorized by severity using multiple imaging modalities, the Bayley Scales of Infant and Toddler Development, third edition (Bayley-III), and semistructured play-based assessments. Of 233 monochorionic twin pregnancies, 138 infants from 69 uncomplicated MCDA pregnancies were included in the final analysis. The mean age at last neurodevelopmental assessment was 26.5 months. Mild neurodevelopmental impairment (NDI) was identified in 29.0% of children and severe NDI, defined as autism spectrum disorder, in 5.8%, while 65.2% had no neurodevelopmental problems. These impairments clustered within twin pairs in most cases. Respiratory distress syndrome was the strongest predictor of mild NDI, whereas higher maternal age OR, 0.92 per year (95% CI, 0.81-1.05) and higher sociocultural level OR, 0.47 (95% CI, 0.14-1.56) were associated with lower risk of both mild and severe NDI. Bayley-III cognitive and motor scores remained stable over time and were comparable to singletons, while language scores declined between 12 and 24 months before stabilizing. No cases of cerebral palsy were observed. The findings suggest that while children born from uncomplicated MCDA twin pregnancies generally have favorable neurodevelopmental outcomes, mild impairment is common and clinically significant. Most of these cases involved language and behavioral difficulties, and autism occurred more frequently than expected based on population estimates. These outcomes were largely independent of gestational age, birth weight, and birth order, though respiratory distress syndrome was associated with mild impairment. Higher maternal age and sociocultural level appeared to attenuate these risks. The results support the need for structured, long-term neurodevelopmental follow-up for all MCDA twins, including those from uncomplicated pregnancies, to facilitate early identification and intervention. (Summarized from Casati D, Lanna MM, Consonni D, et al. Uncomplicated monochorionic twins: Neurodevelopmental insights and implications. Ultrasound Obstet Gynecol. 2025;66(6):724–731. doi: https://doi.org/10.1002/uog.70016)