Relationships of maternal hemodynamics in the third trimester with fetal umbilical artery doppler indices, estimated fetal weight and birth weight in women with and without congenital heart disease

OBJECTIVE: To compare differences in maternal hemodynamics, measured non-invasively by impedance cardiography and mean arterial blood pressure (MAP)-at rest and with high-intensity exercise-between pregnant women with corrected congenital heart disease (CHD) and low-risk (LR) pregnant controls, and to correlate these findings with umbilical artery Doppler in the third trimester, estimated fetal weight (EFW) and birth weight (BW). METHODS: Prospective longitudinal study with hemodynamic exercise studies and fetal ultrasound between 30 and 34 weeks' gestation. Approval was obtained from London South East Research Ethics Committee. RESULTS: There were no differences in heart rate (HR), stroke volume (SV), or cardiac output (CO) at rest between the two groups. HR at peak exercise was significantly lower in the CHD group, and MAP was significantly higher at rest and immediately after exercise. In the CHD group there was a significant association between CO at peak exercise and BW. In the LR group there was a significant association between peak CO with exercise and the abdominal circumference/EFW ratio and between HR at rest and BW. There were no differences in the Doppler indices between groups. There was a statistically significant association between uterine artery Doppler pulsatility index and BW in the LR group, but not in the CHD group. CONCLUSIONS: There was no difference between Doppler indices in the third trimester between a LR population and a population with corrected CHD with no or minimal functional impairment. This suggests that factors other than defective placentation may be causing the lower BW in the CHD population.