Longitudinal maternal hemodynamics from late pregnancy to postpartum in uncomplicated twin pregnancies-A glimpse into long-term cardiovascular risk?

Twin pregnancies impose greater cardiovascular demands than singleton gestations, potentially increasing long-term cardiovascular risk even in the absence of hypertensive disorders. Nevertheless, longitudinal assessments of maternal hemodynamics in uncomplicated twin pregnancies remain limited, and most available studies focus solely on the antenatal period. Chorionicity has been shown to markedly influence cardiovascular adaptation during twin gestation. This study aimed to investigate whether distinct hemodynamic adaptations occur in twin compared with singleton pregnancies during late gestation, 1 day and 6 weeks postpartum.

In this prospective longitudinal cohort study conducted at Hannover Medical School from 08/24 to 05/2025, 36 women with twin pregnancies (8 monochorionic (MC), 28 dichorionic (DC)) and 37 with singleton pregnancies underwent noninvasive hemodynamic assessment at 34 weeks' gestation, 1 day postpartum, and 6 weeks postpartum.

MC twin pregnancies exhibited significantly higher cardiac output (MC: 7.72 L/min; DC: 5.62 L/min; S: 6.27 L/min; p = 0.01) and lower systemic vascular resistance (MC: 958.83 dynes × s/cm⁵; DC: 1206.86 dynes × s/cm⁵; S: 1119.45 dynes × s/cm⁵; p = 0.01) during the third trimester, with a similar hemodynamic pattern appearing to persist in the postpartum period. MC twins also showed significant decreases in heart rate (T1: 86.37 bpm; T2: 77.73 bpm; T3: 66.67 bpm; p = 0.002), mean arterial pressure (T1: 93.0 mmHg; T2: 85.5 mmHg; T3: 78.0 mmHg; p = 0.03), and inotropism postpartum (T1: 1.92 W/m²; T2: 1.67 W/m²; T3: 1.54 W/m²; p = 0.04), whereas DC twins demonstrated a trend to higher stroke volume (T1: 69.6 mL; T2: 80.31 mL; T3: 82.63 mL; p = 0.01) and gradual increase of vascular resistance (T1: 1206.86 dynes × s/cm⁵; T2:1099.86 dynes × s/cm⁵; T3: 1426.78 dynes × s/cm⁵; p = 0.08).

Monochorionic twin pregnancies are characterized by elevated cardiac output and reduced vascular resistance in late pregnancy, with a similar hemodynamic pattern appearing to persist in the postpartum period. This persistent cardiovascular strain may underlie the elevated short-term cardiovascular risk observed after twin births. Our findings highlight the need for larger longitudinal studies to explore the transition from physiological adaptation to potential cardiovascular maladaptation.