Changes of cardiac output during labor in healthy term pregnant women of reproductive age / 中华围产医学杂志

ABSTRACT

Objective:To assess the changes of cardiac output (CO)-related indices in healthy term reproductive age pregnant women during labor.Methods:A prospective longitudinal study was conducted, involving 208 pregnant women at term who were at an reproductive age and admitted to the labor ward of Tianjin Central Hospital of Obstetrics and Gynecology from October 2020 to March 2021. The internal diameter of the aortic root, velocity-time integral of aortic valve flow, and heart rate were obtained through transthoracic echocardiography during uterine contractions period and the intervals between contractions in the latent phase, active phase, and the second stage of labor, as well as at one hour after delivery. Stroke volume (SV), CO, and cardiac index (CI) were then calculated. Comparisons among groups were performed using t-test, analysis of variance, or Wilcoxon test. CO-related indices during contractions periods and intervals between contractions were compared using paired t-test, those in each stage of labor using repeated measurement analysis of variance. Results:(1) CO-related indices in contractions periods vs intervals between contractions during labor In the latent phase, maternal heart rate [79(72 -84) vs 76(70 -85) bpm, Z=－2.03, P<0.05], SV [(77.9±13.4) vs (71.1±12.8) ml, t=－13.98, P<0.05], CO [(6.1 ±1.2) vs (5.5 ±1.1) L/min, t=－14.19, P<0.05], and CI [(3.5 ±0.7) vs (3.1 ±0.6) L/(min·m 2), t=－14.29, P<0.05] during contractions were higher than those during the intervals. These parameters during contractions in the active phase and the second stage of labor were all higher than those during the intervals in the same stage (all P<0.05). (2) CO-related indices in each period of labor Heart rate, CO, and CI during the intervals between contractions gradually increased along with labor progression and reached the peak at the second stage followed by a decrease at one hour after delivery, and a similar trend was also observed for these parameters during contractions in the whole labor (all P<0.05). No significant changes in the maternal SV during intervals between contractions were observed during the labor( P=0.366), while the figure during contractions showed a decreased trend along with the course of labor and declined to a nadir in the second stage (all P<0.05). Conclusions:Cardiac output related indices change significantly in healthy term reproductive age pregnant women during labor, especially in the second stage of labor. Therefore, correct monitoring and management of hemodynamic changes during labor are of great importance in the stability of cardiovascular function throughout labor.