Mode of delivery and perinatal outcomes by modified World Health Organization classification of maternal cardiovascular risk in pregnancy

Abstract

Cardiac disease is a leading cause of maternal morbidity and mortality in the United States, and an increasing number of patients with known cardiac disease are reaching childbearing age. Although guidelines indicate that cesarean deliveries should be reserved for obstetrical indications, rates of cesarean delivery among obstetrical patients with cardiovascular disease are higher than those of the general population. This study aimed to evaluate mode of delivery and perinatal outcomes among patients with low-risk and moderate to high-risk cardiac disease as defined by the modified World Health Organization classification of maternal cardiovascular risk. We performed a retrospective cohort study of obstetrical patients with known cardiac disease, as defined by the modified World Health Organization cardiovascular classification categories in pregnancy, who underwent a perinatal transthoracic echocardiogram at a single academic medical center between October 1, 2017 and May 1, 2022. Demographics, clinical characteristics, and perinatal outcomes were collected. Comparisons were made between patients with low- (modified World Health Organization Class I) and moderate to high-risk (modified World Health Organization Class II-IV) cardiac disease using chi-square, Fisher exact, or Student t-tests. Cohen d tests were used to estimate the effect size between group means. Logistic regression models were used to evaluate the odds of vaginal and cesarean delivery in low- and moderate to high-risk groups. A total of 108 participants were eligible for inclusion, with 41 participants in the low-risk cardiac group and 67 in the moderate to high-risk group. Participants had a mean age of 32.1 (±5.5) years at the time of delivery and a mean pregravid body mass index of 29.9 (±7.8) kg/m2. Chronic hypertension (13.9%) and a history of hypertensive disorder of pregnancy (14.9%) were the most common comorbid medical conditions. In total, 17.1% of the sample had a history of a cardiac event (eg, arrhythmia, heart failure, myocardial infarction). Rates of vaginal and cesarean deliveries were similar between the low- and moderate to high-risk cardiac groups. Patients in the moderate to high-risk cardiac group were more likely to be admitted to the intensive care unit during pregnancy (odds ratio, 7.8; P<.05) and experience severe maternal morbidity compared with patients in the low-risk cardiac group (P<.01). Mode of delivery was not associated with severe maternal morbidity in the higher-risk cardiac group (odds ratio, 3.2; P=.12). In addition, infants of mothers with higher-risk disease were more likely to be admitted to the neonatal intensive care unit (odds ratio, 3.6; P=.06) and have longer neonatal intensive care unit stays (P=.005). There was no difference in mode of delivery by modified World Health Organization cardiac classification, and mode of delivery was not associated with risk of severe maternal morbidity. Despite the overall increased risk of morbidity in the higher-risk group, vaginal delivery should be considered as an option for certain patients with well-compensated cardiac disease. However, larger studies are needed to confirm these findings.