Prolonged labor and adverse cardiac outcomes in pregnant patients with congenital heart disease

Abstract

Background: Patients with congenital heart disease are at high risk for peripartum cardiac morbidity, yet data on the impact of duration of labor on cardiac outcomes are limited. Prolonged labor is a known risk factor for maternal morbidity, but the impact of prolonged labor on cardiac outcomes in patients with congenital heart disease has not been evaluated.

Objective: This study aimed to evaluate the association between prolonged labor (≥24 hours) and adverse peripartum maternal cardiac outcomes in pregnant patients with congenital heart disease.

Study design: This was a retrospective cohort study of pregnant patients ≥18 years with congenital heart disease who received prenatal care and delivered at an academic institution between 1998 and 2020 with a singleton gestation. Pregnancies that ended <20 weeks' gestation and patients who underwent an outright cesarean delivery without exposure to labor were excluded. The primary outcome was a composite adverse maternal cardiac outcome that occurred intrapartum or up to 6 weeks postpartum, defined as the occurrence of 1 or more of the following events: heart failure or clinical volume overload requiring diuresis, pulmonary edema, arrhythmia requiring treatment, thromboembolic complications including deep vein thrombosis or pulmonary embolism, transient ischemic attack, stroke, endocarditis, myocardial infarction, aortic dissection, cardiac arrest, or cardiac death. Outcomes were compared between patients with prolonged labor (≥24 hours) and those without prolonged labor (<24 hours). An interaction between prolonged labor and cesarean delivery was evaluated.

Results: A total of 229 patients were included. The median duration of labor was 14 hours, and 18% of patients labored for ≥24 hours. Overall, 11.8% experienced the composite cardiac outcome with a significantly higher rate in the prolonged labor group (22% vs 9.6%; P=.03). After adjusting for confounders, including nulliparity, labor induction, gestational age, and World Health Organization class, there was a 2.7-fold increase in the odds of the composite cardiac outcome for patients who experienced prolonged labor (adjusted odds ratio, 2.7; 95% confidence interval, 1.1-7.1). There was no significant difference in cardiac outcome between those who had a vaginal delivery and those who had a cesarean delivery during labor (10.0% vs 16.1%; P=.18). There was, however, a significant interaction between prolonged labor and cesarean delivery; after adjustment for confounders, patients who underwent a cesarean delivery after prolonged labor had a 6.8-fold increase in the odds of experiencing the composite cardiac outcome when compared with those who underwent a cesarean delivery without prolonged labor (30.8% vs 7.1%; adjusted odds ratio, 6.8; 95% confidence interval, 1.4-32.5), most commonly, heart failure or volume overload requiring diuresis.

Conclusion: In a cohort of pregnant patients with congenital heart disease, prolonged duration of labor ≥24 hours was significantly associated with an increased risk for an adverse peripartum cardiac outcome, especially among those who underwent a cesarean delivery after that time. These findings suggest that close attention should be paid to the duration of labor, and those who require a cesarean delivery after a prolonged labor should be monitored closely for signs of volume overload and other adverse cardiac events.

Keywords: cardiac disease in pregnancy; congenital heart disease; maternal morbidity; mode of delivery; prolonged labor.