Uterine artery and umbilical vein blood flow are unaffected by moderate habitual physical activity during pregnancy

• Published in: Prenatal diagnosis Vol. 39; no. 11; pp. 976 - 985
• Main Authors: Sussman, Dafna, Saini, Brahmdeep S., Schneiderman, Jane E., Spitzer, Rachel, Seed, Mike, Lye, Stephen J., Wells, Greg D.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-10-2019
• Subjects: Arteries; Blood flow; Body mass; Body mass index; Body size; Decoupling; Exercise; Fetuses; Heart rate; Hemodynamics; Magnetic resonance imaging; Mechanical ventilation; NMR; Nuclear magnetic resonance; Oxygen consumption; Oxygen uptake; Parameters; Physical activity; Physical fitness; Placenta; Pregnancy; Quotients; Regression analysis; Regression models; Respiratory quotient; Umbilical vein; Uterus; Veins; Ventilation
• ISSN: 0197-3851; 1097-0223
• DOI: 10.1002/pd.5517

Objective
This study aims to noninvasively quantify blood flow in the uterine arteries (UTAs) and umbilical vein (UV) using phase‐contrast magnetic resonance imaging (PC‐MRI) and test whether these correlate with maternal fitness parameters.
Method
Resting UTA and UV flows were measured in 23 healthy 30 ± 3‐year‐old women who engaged in moderate‐intensity physical activity during pregnancy. Participant fitness was characterized in the second and third trimesters using the submaximal oxygen uptake (VO2) test measuring heart rate (HR), VO2, ventilation (ventilatory equivalent [VE]/VO2), and the Borg rating of perceived exertion (respiratory quotient [RQ]). Linear regression models were used to determine the associations between blood flow and maternal fitness measures.
Results
Blood flows in the UTA (957 ± 241 mL/min) and UV (132 ± 38 mL/min/kg) were successfully measured in 20 (87%) participants. Neither was associated with any physical fitness parameters (HR, VO2, VE/VO2, and RQ) nor with any second‐to‐third trimester change in these parameters.
Conclusion
PC‐MRI can be used to noninvasively measure blood flow in the UTA and UV. Neither resting UTA nor UV flow is associated with maternal fitness parameters. This is the first MRI–based study to provide novel hemodynamic data suggesting decoupling between maternal moderate fitness level and the maternal‐placental‐fetal hemodynamic system in healthy, normal body mass index (BMI) pregnancies.
What's already known about this topic?
Adopting or continuing a moderately active lifestyle during an uncomplicated pregnancy is currently recommended worldwide by a variety of expert committees on exercise and pregnancy.
A relationship between exercise and the cardiovascular system has been proposed in the literature and backed up by studies showing an impact on endothelial function, myocardial reserve, placental vascular proliferation, and maternal and fetal heart rates.
What does this study add?
This study provides the first accurate MRI‐based measurements of both resting UTA and UV blood flows as a function of maternal physical fitness in normal pregnancies.