Placental histopathology differences and neonatal outcome in dichorionic–diamniotic as compared to monochorionic–diamniotic twin pregnancies

Objective: We aimed to compare the differences in placental histopathology lesions and pregnancy outcome in dichorionic– diamniotic (DCDA) versus uncomplicated monochorionic–diamniotic (MCDA) twin gestations. Study Design: Maternal characteristics, neonatal outcome, and placental histopathology reports of all twin deliveries between 24 and 41 weeks were reviewed. Excluded were pregnancies complicated by twin-to-twin transfusion syndrome, twin anemia–polycythemia sequence, selective intrauterine growth restriction, placenta previa, intrauterine fetal death, and malformation. Placental lesions were classified to maternal/fetal vascular malperfusion lesions. Umbilical cord abnormalities included hypo-/hypercoiling and abnormal insertion. Composite adverse neonatal outcome was defined as 1 or more early complications. Small for gestational age (SGA) was defined as birth weight ≤10th percentile. Results: The DCDA group (n = 362) was characterized by higher rates of assisted reproductive techniques (P <.001) and nulliparity (P =.03) as compared to the MCDA group (n = 65). Gestational age at delivery was similar between groups. Placental maternal vascular malperfusion lesions were more common in placentas from DCDA group (38.2% vs 23.1%; P =.016), while fetal vascular malperfusion lesions and abnormal cord insertion were more common in placentas from MCDA group (P =.027; P <.001). The SGA and composite adverse neonatal outcome were more common in the MCDA group (P =.031 and P =.038, respectively). By multivariate regression analysis, composite adverse neonatal outcome was found to be independently associated with the MCDA group, adjusted odds ratio (aOR) = 1.2, 95% confidence interval (CI) = 1.04 to 1.89, P =.041, and with placental fetal malperfusion lesions aOR = 1.3, 95% CI = 1.1 to 2.09, P =.038. Conclusion: Placental pathology differs between MCDA and DCDA twin pregnancies. Adverse neonatal outcome in uncomplicated MCDA twins, as compared to DCDA twins, could be related to increased placental fetal malperfusion lesions and abnormal cord insertion.