Abstract

OBJECTIVE: Pregnancies complicated by fetal growth restriction (FGR) have worse outcomes than pregnancies with a small for gestational age (SGA) fetus. There is increasing evidence of a maternal cardiovascular role in the pathophysiology. We aimed to compare the maternal hemodynamic indices (cardiac output and systemic vascular resistance) in pregnancies complicated by FGR and pregnancies with an SGA fetus using a non-invasive device (USCOM-1A®). METHODS: This was a prospective study of normotensive pregnancies complicated by FGR (defined as pregnancies with a birthweight <3rd centile or with Doppler evidence of impaired placental-fetal blood flow), pregnancies with an SGA fetus (defined as pregnancies with a birthweight <10th centile) and control pregnancies (defined as having an appropriately-grown fetus). Assessment of the maternal hemodynamics was performed using a non-invasive device (USCOM-1A®). Hemodynamic variables that are affected by gestational age and maternal characteristics were corrected for using device-specific reference ranges. Statistical analysis was performed using the Chi-square test and the Mann-Whitney test. RESULTS: A total of 102 FGR, 64 SGA and 401 control pregnancies at 28-41 weeks' gestation were included in the analysis. Women with pregnancies complicated by FGR and pregnancies with an SGA fetus were shorter and weighed less than controls. The FGR group had significantly lower median heart rate (80bpm vs 85bpm, p=0.001), lower cardiac output (0.91MoM vs 0.98MoM, p=0.003), higher mean arterial pressure (90mmHg vs 87 mmHg, p= 0.040), higher systemic vascular resistance (1.2MoM vs 1.0MoM, p<0.001) and higher uterine artery pulsatility index (1.1MoM vs 0.96MoM, p<0.001) compared to controls, but there was no significant difference in stroke volume (p=0.647). The FGR group had a significantly lower median heart rate (80bpm vs 87bpm, p=0.022), higher mean arterial pressure (90mmHg vs 85 mmHg, p=0.025), higher systemic vascular resistance (1.2MoM vs 1.0MoM, p=0.002) and higher uterine artery pulsatility index (1.1MoM vs 0.98MoM, p=0.005) compared to the SGA group, but there was no significant difference in cardiac output (0.91MoM vs 0,96MoM, p=0.092) or stroke volume (1.0MoM vs 1.0MoM, p=0.806). There were no significant differences in maternal hemodynamic indices between the SGA and control groups. CONCLUSION: Pregnancies complicated by FGR present with worse maternal hemodynamic function, as evidenced by lower heart rate and cardiac output as well as higher mean arterial pressure, systemic vascular resistance and uterine artery resistance. Pregnancies resulting in a SGA neonate, without evidence of FGR have normal maternal hemodynamic function. Maternal hemodynamic indices may be of value in distinguishing FGR from SGA pregnancies. This article is protected by copyright. All rights reserved.