Haemodynamic changes during labour: continuous minimally invasive monitoring in 20 healthy parturients.

BACKGROUND: There are few studies on maternal haemodynamic changes during labour. None have used continuous cardiac output monitoring during all labour stages. In this observational study, we monitored haemodynamic variables continuously during the entire course of labour in healthy parturients.

METHODS: Continuous haemodynamic monitoring with the LiDCOplus technique was performed in 20 healthy parturients during spontaneous labour, vaginal delivery and for 15minutes postpartum. Cardiac output, stroke volume, heart rate, systemic vascular resistance, and systolic arterial pressure were measured longitudinally at baseline (periods between/without contractions) and during contractions in early and late stage 1, stage 2, during delivery, and postpartum, and were analysed with marginal linear models.

RESULTS: Twenty parturients were included. In early stage 1, baseline cardiac output was 6.3L/min (95% CI 5.7 to 6.9). Baseline values were similar across both labour stages and postpartum for all haemodynamic variables. During stage 2 contractions, cardiac output decreased by 32%, stroke volume decreased by 44%, heart rate increased by 52%, systemic vascular resistance increased by 88%, and systolic arterial pressure increased by 36% compared to baseline. During stage 1 contractions, haemodynamic changes were less profound and less uniform than during stage 2.

CONCLUSION: Progression of labour had no major effect on haemodynamic baseline values. Haemodynamic stress during contractions was substantial in both labour stages, yet most pronounced during the second stage of labour. The absence of an increase in stroke volume and cardiac output postpartum questions the common belief in an immediate rise in cardiac output after delivery due to autotransfusion from the contracted uterus.