National Perinatal Information Center
National Perinatal Information Center


The Adverse Outcome Index (AOI) analysis is designed to measure the volume and magnitude of ten adverse events that occur during or around the delivery process and may expose an obstetrical team to malpractice liability. Events that are definable, as well as potentially modifiable through improved teamwork, are included.

The ten types of adverse events are:
  • In-Hospital Maternal Death
  • In-Hospital Neonatal Death ≥ 2500 Grams and ≥ 37 Weeks Gestation
  • Uterine Rupture During Labor
  • Unplanned Maternal Admission to ICU
  • Birth Trauma
  • Unanticipated Operative Procedure
  • Admission to NICU of Neonate ≥ 2500 Grams and ≥ 37 Weeks Gestation for > 1 Day
  • APGAR 5 < 7
  • Maternal Blood Transfusion
  • 3rd or 4th Degree Perineal Laceration

Each type of event has a severity weight, developed by a panel of experts. Three indices are calculated: the Adverse Outcome Index (AOI), the Weighted Adverse Outcome Score (WAOS), and the Severity Index (SI)).

NPIC/QAS has been providing AOI Reports as a service to hospitals since 2007. NPIC/QAS partners with developers of the AOI to refine the algorithm used to identify the number of adverse events per quarter using the UB-04 administrative data set and supplemental data submission. The current version of the algorithm is 3.0

A Quarterly Monitoring Report displays 16 quarters of data and includes a trend data analysis, with valuable comparison data from NPIC/QAS member hospitals who receive AOI reports. Target benchmarks reflect data from member hospitals in the top performance quartile for the WAOS metric.

A Pre-Post Quality Improvement Report is provided if a hospital has implemented significant process improvement strategies within a particular time period. An additional analysis determines if there is a significant improvement in the indictors from baseline to follow-up (e.g., post team training).

Researchers implementing projects to improve perinatal care have collaborated with NPIC/QAS to provide participating hospitals with pre-post QI reports that include AOI metrics.

Related Research Projects:
  • Safety Program for Perinatal Care,
    sponsored by AHRQ through contract
    to RTI International

  • The Premier Perinatal Safety Initiative

NPIC/QAS AOI reporting is an efficient and cost-effective way to monitor quality improvement.
Adverse Outcome Index (AOI) "Best Practices" Webinar

NPIC/QAS member hospitals share their experiences using the Adverse Outcome Index (AOI) to reduce harm in their Perinatal Services. » Learn More

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