Fetal cardiac output and its distribution to the placenta at 11-20 weeks of gestation

Abstract

Objectives To measure serial changes in cardiac output (CO) and its fraction distributed to the placenta at 11 -20 weeks of gestation. Methods Blood flow velocities, and diameters of the aorta, pulmonary artery and umbilical vein, were measured longitudinally in 143 fetuses using ulsed-wave Doppler and two-dimensional ultrasound examination. Results Volume blood flow of the aorta (left ventricular CO) and the pulmonary artery (right ventricular CO) increased in a similar manner with advancing gestational age. The combined cardiac output (CCO) increased from 9 mL/min to 121 mL/min, and the placental volume blood flow (Q uv) increased from 1.2 mL/min to 25.3 mL/min during 11 -20 weeks of gestation. The fraction of CCO diverted to the placenta increased from 14% at 11 weeks to 21% at 20 weeks. Conclusions We have established longitudinal reference ranges for fetal CO and Q uv at 11 -20 weeks ofgestation. The fraction of CCO distributed to the placenta increased significantly during this period, reflecting rapid placental growth and establishment of a low-resistance circulation. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.