Maternal Mortality Data: Gains in Accuracy and Timeliness

The “Quality Gap” in Maternal Death Data

Maternal Mortality is a critical indicator of the health of women, families, and communities. Reliable data are essential for identifying disparities, tracking trends, and informing prevention strategies. Within the Division of Vital Statistics (DVS) in CDC’s National Center for Health Statistics (NCHS), ensuring the accuracy of these data is a top priority.

In the United States, NCHS produces official maternal mortality statistics through the National Vital Statistics System (NVSS), a collaboration between NCHS and the 57 vital records jurisdictions (50 states, 5 U.S. territories, the District of Columbia, and New York City). Historically, maternal deaths were often underreported because medical certifiers did not include sufficient information in the cause-of-death section of the certificate to identify that the decedent was pregnant or had recently been pregnant.

To address this issue, the U.S. Standard Certificate of Death was revised in 2003 to include a checkbox for reporting that a decedent had been pregnant at the time of death or at any time during the year preceding death. Despite its intent, the checkbox introduced challenges of its own. Although it successfully identified maternal deaths that might have been missed, errors by medical certifiers when selecting a checkbox led to overreporting of maternal deaths.

Moving Beyond the Initial Report

Although NCHS implemented procedures to minimize errors in statistical data, ongoing evaluations indicated the need to expand efforts to improve data quality. In 2023, NCHS shifted from a passive reporting model to an active verification process by asking jurisdictions to verify checkbox information for deaths reported to have occurred during pregnancy.

This effort was expanded in 2024 to include deaths for women reported to have been pregnant in the year preceding death. Jurisdictions now receive quarterly listings of these records and verify checkbox information through follow-up with medical certifiers and comparison with other data sources. This approach is improving data quality.

The pregnancy checkbox is no longer treated as a standalone solution but as part of a broader quality assurance framework, ensuring that NCHS-reported maternal mortality data are as accurate as possible. Complementing this approach, NCHS also offers medical certifiers guidance and online training to improve accuracy at the source.

Turning Data into Insight

Enhanced verification confirmed what early assessments suggested: without additional review, pregnancy checkbox data can contain systematic errors. Of the records that jurisdictions were able to verify in 2024, about 26% contained pregnancy checkbox errors. Although many of these records involved decedents aged 45 or older who had not been pregnant in the year before death—records that would have been corrected under procedures in place since 2018—a substantial number of errors were detected in the records of younger women.

This highlighted the value of the new procedures for improving data quality. By incorporating verification into routine NVSS operations, errors are identified and corrected, thus strengthening the accuracy and reliability of maternal mortality data.

New Standard for Timeliness and Accuracy

Data must be both accurate and timely to effectively inform public health decisions. Integrating verification into the NVSS workflow allows NCHS to confirm pregnancy status throughout the year and correct errors as records are amended. This enables NCHS to release timelier and more accurate provisional maternal mortality data through weekly CDC WONDER updates and quarterly .

“Timely and accurate data are essential for developing effective strategies to prevent maternal deaths.” – Paul Sutton, PhD, Director, Division of Vital Statistics, NCHS

A Modernized Foundation for Maternal Health

Modernized processes enable more timely and complete data, and efforts are underway to automate the process for jurisdictions to verify maternal death data and provide linked birth and fetal death data to NCHS.

Rigorous and timely verification creates a foundation of increased reliability, providing confidence that the trends that public health officials observe and that inform public health action are based on the most accurate and timely information possible.