OC25.07: Maternal hemodynamics in small‐for‐gestational‐age pregnancies with and without fetal growth restriction

Abstract

Small-for-gestational-age (SGA) pregnancies, and in particular those with fetal growth restriction (FGR) are associated with an increased risk of adverse outcomes. Abnormal uterine artery (UtA) Doppler and other measures of maternal hemodynamics appear to be independently associated with adverse fetal outcome. The aim of this study was to describe the maternal hemodynamic differences in normotensive, SGA pregnancies with and without FGR. This was a prospective study of SGA and control pregnancies. Measurements of maternal hemodynamics, using a non-invasive device (USCOM-1A) were obtained. Variables that are affected by gestational age and maternal characteristics were corrected for using device-specific reference ranges. Pregnancies with evidence of FGR were compared to those with SGA only and normal pregnancies using descriptive statistics. Statistical analysis was performed using the Chi-squared test and Mann-Whitney test. A total of 102 FGR, 64 SGA and 401 control pregnancies at 28-41 weeks were included in the analysis. Compared to controls, the FGR group had significantly lower median heart rate (HR) (80bpm vs 85bpm, p = 0.001), lower cardiac output (CO) (0.91MoM vs 0.98MoM, p = 0.003), and higher systemic vascular resistance (SVR) (1.2MoM vs 1.0MoM, p < 0.001). There was no significant difference in stroke volume (SV) (1.0MoM vs 0.98MoM, p = 0.647) between the FGR and normal pregnancy groups. In contrast, there were no significant differences in maternal hemodynamics between the SGA and control groups. FGR pregnancies present with maternal cardiovascular dysfunction, as evidenced by lower HR and CO as well as higher mean arterial pressure (MAP), SVR and UtA resistance. SV is unchanged in FGR pregnancy suggesting that the observed drop in CO is a consequence of lower maternal HR. Pregnancies resulting in SGA neonate, without evidence of fetal hypoxemia or adverse outcome have normal cardiovascular adaptation. Maternal HR and other hemodynamic parameters may be of value in distinguishing SGA from FGR.