Doppler examinations of fetal and uteroplacental blood flow in AGA and IUGR fetuses before and after maternal physical exercise with the bicycle ergometer

Abstract

Objective: To study changes in uteroplacental and fetal circulation after maternal exercise in appropriate-for-gestational-age fetuses (AGA) and intrauterine-growth-retarded fetuses (IUGR).

Materials and method: 33 women with an uncomplicated course of pregnancy and ten women with IUGR were examined. Physical stress was caused through a bicycle ergometer with 1.25 W/kg maternal weight. Doppler examinations were performed in the umbilical artery, fetal aorta, middle cerebral and in the uterine artery. Fetal heart rate was documented by monitoring. Maternal lactate and glucose levels as well as maternal blood pressure and heart rate were recorded.

Results: No significant changes after cycling could be observed in umbilical and uterine vessels either in the normal pregnancies or in pregnancies with IUGR. In contrast, in the fetal aorta an increase of the RI was recorded in both groups (an increase of 16% [P<0.01] and 18% [P<0.05], respectively for AGA and IUGR cases). In cerebral arteries a decrease of the RI was observed after cycling in both groups (a decrease of 24% [P<0.01] and 13% [P<0.05], respectively for AGA and IUGR cases). In AGA fetuses the RI of the aorta and middle cerebral artery returned to pre-test level by the 18th minute of examination. In IUGR fetuses the RI of the aorta and middle cerebral artery did not return to pre-test levels at the end of the test. Fetal heart rate remained unchanged in both groups. Maternal blood pressure and heart rate increased during the exertion phase but returned to initial values at the end of the test. A 21% and 24% (for AGA and IUGR groups respectively) reduction of maternal glucose values after exercise was observed (P<0.001). Lactate values doubled in both groups after exercise (P<0.001).

Conclusion: From the results obtained we conclude that maternal exercise does not significantly alter uterine and umbilical perfusion in AGA and IUGR pregnancies, suggesting an absence of change in the uterine vascular bed resistance. However, submaximal maternal exercise was followed by fetal cerebral vasodilatation and an increase of resistance in the fetal aorta that was more evident in IUGR fetuses. This might be due to slight fetal hemoglobin desaturation in those cases.