Placental Accrete Spectrum Increases Risk for Amniotic Fluid Embolism, Mortality

Placental accrete spectrum was note previously associated with amniotic fluid embolism.

A study published in JAMA Network Open found that severity of placental accrete spectrum (PAS) is associated with amniotic fluid embolism (AFE) and significant maternal mortality at time of delivery.

Investigators sourced data for this study from the National Inpatient Sample (NIS). Patients (N=14,684,135) who had a vaginal or cesarean delivery between 2016 and 2019 were evaluated for risk factors and outcomes associated with AFE.

The cohort comprised women aged a median of 29 (IQR, 25-33) years; 50.4% were White and 63.8% delivered vaginally at 39 weeks’ gestation or later.

A total of 880 AFE events occurred (incidence rate, 6.0 per 100,000 pregnancies) and 150 maternal deaths were recorded. This rate had been increasing over time from a rate of 5.2 per 100,000 pregnancies in 2016 to 6.5 per 100,000 pregnancies 2019 (P =.04).

AFE is a rare pregnancy complication and is associated with significant maternal outcome.

In the multivariate analysis, increased AFE risk was associated with 26 patient characteristics. The features which were most highly linked to increased risk included:

  • PAS: adjusted odds ratio (aOR), 10.01; 95% CI, 7.03-14.24; P <.001;
  • Delivery at unknown gestational age compared with 39 weeks or later: aOR, 9.81; 95% CI, 7.76-12.38; P <.001;
  • Delivery by cesarean compared with vaginal delivery: aOR, 6.41; 95% CI, 5.38-7.64; P <.001;
  • Vacuum assisted delivery compared with vaginal delivery: aOR, 4.95; 95% CI, 3.55-6.88; P <.001;
  • Placental abruption: aOR, 4.06; 95% CI, 3.17-5.21; P <.001; and
  • Uterine rupture: aOR, 3.91; 95% CI, 2.07-7.36; P <.001.

Decreased risk for AFE was associated with Hispanic ethnicity compared with White ethnicity (P =.03), and private insurance (P =.009) or self-pay (P =.02) compared with Medicaid.

Altogether, women who experienced PAS, placental abruption, and late-preterm or early-term delivery were at the highest risk for AFE.

The women who experienced AFE were also at increased risk for disseminated intravascular coagulation, cardiac arrest or ventricular fibrillation, adult respiratory distress syndrome, cardiac rhythm conversion, shock, heart failure or arrest, blood transfusion, and eclampsia (aOR range, 2.96-24.68; all P <.001).

Women who were at greatest risk for failure to rescue had AFE and PAS (>40%) and AFE and placental abruption (>30%).

The major limitation of this study is unavailability of chronological data.

“AFE is a rare pregnancy complication but is associated with significant maternal outcome,” according to study authors. This is the first study to find an association between AFE and PAS, and this relationship warrants additional research. “The association of PAS with AFE was unexpected because this observation was not reported previously.”

Disclosure: One author declared affiliations with industry. Please refer to the original article for a full list of disclosures.


Mazza GR, Youssefzadeh AC, Klar M, et al. association of pregnancy characteristics and maternal mortality with amniotic fluid embolism. JAMA Netw Open. Published online November 18, 2022. doi:10.1001/jamanetworkopen.2022.42842