Maternal cardiovascular function and risk of intrapartum fetal compromise in women undergoing induction of labor: a pilot study

OBJECTIVE: Identification of the fetus at risk of intrapartum compromise has many benefits. Impaired maternal cardiovascular function is associated with placental hypoperfusion intrapartum fetal distress. The main aim of this study was to assess the predictive accuracy of maternal hemodynamics for the risk of operative delivery due to presumed fetal compromise in women undergoing induction of labour (IOL). METHODS: In this prospective cohort study patients were recruited between November 2018 and January 2019. Women undergoing IOL were invited to participate in the study. A non-invasive ultrasonic cardiac output monitor (USCOM-1A) was used for the cardiovascular evaluation. The study outcome was operative delivery due to presumed fetal compromise, which included cesarean or instrumental delivery for abnormal fetal heart monitoring. Regression analysis was used to test the association between cardivascular markers, as well as the maternal characteristics and the risk of operative delivery for presumed fetal compromise. The ROC curve analysis was used to assess the predictive accuracy of the cardivascular markers for the risk of operative delivery for presumed fetal compromise. RESULTS: A total of 99 women were recruited and four women were later excluded from the analysis due to semi-elective cesarean section (n=2) and failed IOL (n=2). The rate of operative delivery due to presumed fetal compromise was 28.4% (27/95). Women who delivered without suspected fetal compromise were more likely to be multiparous (52.9% vs 18.5%, p=0.002). Women who underwent operative delivery due to presumed fetal compromise had significantly lower cardiac index (CI) (median: 2.50 L/min/m2 vs. 2.60 L/min/m2 , p=0.039) and higher systemic vascular resistance (SVR) (median: 1480.0 mmHg.min.mL-1 /m2 vs. 1325.0 mmHg.min.mL-1 /m2 , p=0.044) compared to controls. The baseline model (multiparity only) showed poor predictive accuracy with an area under the curve (AUC) value of 0.67 (95% CI: 0.58-0.77). The addition of stroke volume index (SVI) 7.2 logs or SVR index (SVRI) >7.7 logs significantly improved the baseline model (p=0.012, p=0.026 and p=0.012, respectively). CONCLUSION: In this pilot study, we demonstrated that pre-labour maternal cardiovascular assessment in women undergoing IOL could be useful for assessing the risk of intrapartum fetal compromise necessitating operative delivery. The addition of SV, SVR and SVRI significantly improved the predictive accuracy of the baseline antenatal model. This article is protected by copyright. All rights reserved.