Maternal circulation in twin pregnancies with twin-twin transfusion syndrome

Twin pregnancies are a risk factor for perinatal cardiomyopathy, and the enlarged uterus leads to decreased venous return due to compression of the inferior vena cava (IVC). It has not been clarified, the effect of twin–twin transfusion syndrome (TTTS) itself on maternal circulation. In this study, we examined changes in maternal circulation at the onset of TTTS. This cohort study was conducted at Toho University Omori Hospital from October 2022 to January 2023. The patients were divided into three groups: singleton pregnancy group (singleton group), uncomplicated mono-chorionic diaphragmatic twin pregnancies (nMD group), and TTTS cases (TTTS group). We prospectively collected data by echocardiography performed to evaluate left ventricular function: left ventricular contractility, diastolic performance, and IVC diameter. This study was approved by the Ethics Committee of Toho University Omori Hospital. During the study period, there were 16 cases in the singleton group, 8 cases in the nMD group, and 7 cases in the TTTS group. Maternal age was 35 (26-42), 30 (27-40), and 34 (28-36) years in the singleton, nMD, and TTTS groups, respectively (p = 0.35). BMI at measurement was no significant difference between the three groups (p = 0.39). Systolic left ventricular volume was significantly lower in the TTTS group [10(0.8-22)ml] than in the singleton group [16.5 (5.3-50) ml] and the nMD group [23.9 ± 10.2ml] (p = 0.048). Left ventricular diastolic performance of septal mitral valve E/e' had significant differences among the three groups (p = 0.024): 7.74 ± 1.53 in the singleton group, 6.64 ± 0.80 in the nMD group, and 9.44 (5.9-10.50) in the TTTS group. 50)ml] and the nMD group [23.9 ± 10.2ml] (p = 0.048). Left ventricular diastolic performance of septal mitral valve E/e' had significant differences among the three groups (p = 0.024): 7.74 ± 1.53 in the singleton group, 6.64 ± 0.80 in the nMD group, and 9.44 (5.9-10.50) in the TTTS group. The results suggest that TTTS itself may have an adverse effect on maternal left ventricular diastolic function compared to uncomplicated singleton or MD twins.