Cardiac arrest occurs in one in 9,000 pregnant patients during hospital delivery

Key takeaways

• The cardiac arrest rate from 2017 to 2019 was 13.4 per 100,000 delivery hospitalizations, higher than previous estimates.
• Of the patients who had cardiac arrest, 68.6% survived to hospital discharge.
• The most common co-occurring diagnosis was acute respiratory distress syndrome.

Cardiac arrest occurred in about one in every 9,000 delivery hospitalizations from 2017 to 2019 in the United States, and about seven in 10 women survived the event, according to the results published in Annals of Internal Medicine.

Nicole D. Ford, PhD, MPH, an epidemiologist at the CDC, and colleagues wrote that “cardiac arrest is an uncommon but serious maternal complication,” and current estimates of cardiac arrest that occur during delivery guide evidence-based strategies that aim to reduce pregnancy-related deaths.

“Maternal cardiac arrest is an indicator of severe maternal morbidity — that is, unexpected outcomes of labor and delivery that result in significant short- or long-term health consequences,” the researchers wrote. “If not identified and treated promptly, these conditions can lead to pregnancy-related death.”

The researchers conducted a retrospective cohort study to estimate the rates of cardiac arrest during delivery hospitalization, along with any maternal characteristics that might be associated with the events.

Ford and colleagues used data on delivery hospitalizations in U.S. acute care hospitals from 2017 to 2019 among women aged 12 to 55 years who were included in the National Inpatient Sample database.

They found that, among more than 10 million delivery hospitalizations, the cardiac arrest rate was 13.4 per 100,000 (95% CI, 11.9-14.9), and remained stable during the 3-year period. The researchers noted that cardiac arrest was most common in patients who were Black, older, had underlying medical conditions or had Medicare or Medicaid, which is “consistent with existing literature on maternal cardiac arrest.”

Of the 1,465 patients who had cardiac arrest, nearly 70% survived to hospital discharge — 68.6% (95% CI, 63.2-74). However, this rate was lower with co-occurring disseminated intravascular coagulation (DIC) without or with transfusion: 50% (95% CI, 35.8-64.2) or 54.3% (95% CI, 39.2-69.5), respectively.

“Survival to hospital discharge after cardiac arrest was lowest with co-occurring DIC,” Ford and colleagues wrote. “However, we could not determine causality or identify whether co-occurring severe maternal complications preceded or followed cardiac arrest. We also could not distinguish the causes of cardiac arrests, including whether they were pregnancy-related complications or other underlying causes among pregnant women.”

The researchers additionally noted that the most common co-occurring diagnosis was acute respiratory distress syndrome, at 56% (95% CI, 50.2-61.7), but mechanical ventilation was the most common co-occurring procedure or intervention examined at 53.2% (95% CI, 47.5-59).

“Although acute respiratory distress syndrome was the most common co-occurring diagnosis, cardiac arrest rates were high among hospitalizations where a diagnosis of amniotic fluid embolism was noted,” they wrote.

Ford and colleagues noted that the rate of cardiac arrest in the current study was higher than previously published estimates.

“More information is needed on specific drivers of cardiac arrest frequency, including race and ethnicity; underlying medical conditions; and other patient-, hospital-, and community-level characteristics,” the researchers wrote. “Implementing clinical guidelines, ensuring that pregnant people receive risk-appropriate care, and addressing potential knowledge deficits in maternal cardiac arrest and cardiopulmonary resuscitation technique for pregnant people may improve maternal outcomes.”