Normal cardiac ventricular geometry and function during the last trimester of pregnancy and early neonatal period.

Fetal and early neonatal left and right ventricular cardiac geometry and left ventricular cardiac function were studied by M-mode technique in a cross-sectional study between 28 and 40 weeks of gestation (n = 227) and a longitudinal study from 24 h before until 48 h after delivery (n = 15). Antenatally both ventricles were geometrically uniform; there was a 3.2-3.4-fold increase in left ventricular volume and a nearly 3-fold increase in left ventricular stroke volume and cardiac output. During the early neonatal period the right ventricular transverse diameter reduced in size; there was a further 1.1-fold rise in left ventricular volume and a further 1.2-1.3-fold rise in the left ventricular stroke volume and cardiac output.