Deaths during pregnancy or the postpartum period are relatively rare, affecting less than 1,000 U.S. women in most years.
Yet maternal mortality is a key indicator of health care quality. Most maternal deaths are preventable because steps to avoid or manage life-threatening complications are well known, according to the World Health Organization (WHO).
Further, the agency says, “Maternal health and newborn health are closely linked.”
However, counting maternal deaths is complicated. The U.S. has three different reporting systems, and their results frequently don’t agree.
Here’s a primer.
One source of data, three reporting systems
All maternal mortality statistics originate with death certificates, which may be completed by an attending or primary physician, nurse practitioner, medical examiner, coroner or other person, depending on state law. That information goes to three distinct reporting systems with different strengths and limitations.
The National Center for Health Statistics publishes the official U.S. maternal mortality rate, which is used for international comparisons. It’s also known as the National Vital Statistics System.
- What it measures: Maternal mortality as defined by the WHO, which is death during pregnancy or within 42 days of the end of pregnancy from any cause “related to or aggravated by the pregnancy or its management.” Deaths are classified using ICD-10 codes.
- Pluses: Data are broken down by state, age group, education level, county urbanization, and race and Hispanic origin. Reporting has a relatively short time lag, typically a little more than a year.
- Minuses: The brief time frame of 42 days misses deaths that occur well after pregnancy. The adoption of a pregnancy checkbox on death certificates has led to improved identification of deaths during pregnancy that were missed in the past but also significant overcounting of maternal deaths.
The CDC runs a separate Pregnancy Mortality Surveillance System.
- What is measures: Pregnancy-related deaths, which are deaths “while pregnant or within one year of the end of pregnancy from any cause related to or aggravated by the pregnancy.” Deaths are classified by medical epidemiologists.
- Pluses: In addition to death certificates, the system draws on other sources such as birth and fetal death certificates. Records are reviewed to determine whether a death was pregnancy-related. The extended time frame captures deaths that occur more than 42 days after pregnancy.
- Minuses: Pregnancy-related mortality is not released for individual states. There’s a long time lag, with the most recent data dating from 2019.
Maternal mortality review committees exist in most states as well as New York City, Puerto Rico, Philadelphia and Washington, D.C., according to the Guttmacher Instititute.
- What they measure: Pregnancy-associated deaths, which are deaths of any cause that occur within a year of pregnancy. Deaths are classified by multidisciplinary committees into preganancy-related or pregnancy-associated (but not related).
- Pluses: These experts use a variety of sources including medical and social service records and interviews to investigate individual deaths, including those tied to social issues such as homicide, suicide and overdose. They gather insights into trends in their jurisdiction and recommend improvements in local health and social systems that serve women.
- Minuses: Reports may be several years old and lack comparisons with national benchmarks, although the CDC compiled committees’ work in a report of 2017-2019 data from 36 states.
Journalists may also want to examine trends in severe maternal morbidity, which is more common. There are two sources for state data, which are based on hospital discharge data from billing records. Current data are for 2020.
- The Agency for Healthcare Research and Quality Healthcare Cost and Utilization Project Fast Stats
- The Health Resources and Services Administration’s Title V Maternal and Child Health Services Block Grant Reporting, with additional breakdowns for insurance status, race/ethnicity, rural/urban, and other factors. (Select National Outcome Measure 2.)
Ask experts such as public health officials and chairs of state review committees what’s driving the numbers and why surveillance methods produce different estimates and trends.
Consider methodology changes that could hamper the identification of trends. One example is the phase-in of a pregnancy checkbox on death certificates between 2003 to 2017, which roughly doubled the observed national maternal mortality rate.
Marie Thoma, Ph.D., a population health scientist at the University of Maryland, said in an interview that journalists can identify general trends in maternal mortality in a given state using these different data sources as long as the methodology remains consistent from year to year.
What the data show
These reporting systems do reveal themes that can drive story ideas. Here are some key ones:
- The U.S. lags behind our peers. Even by the most conservative measures, the U.S. has significantly higher maternal mortality than other large industrialized countries.
- Racial disparities persist. Surveillance shows that Blacks and American Indian/Alaskan natives in particular have dramatically higher maternal mortality rates. Geographic differences explain only some of the differences.
- Many deaths occur well after birth. Data from maternal mortality review committees show that 53% of deaths occur a week to a year postpartum, in part because of mental health factors that lead to drug overdose and suicide. Evidence suggests recent improvement in care at the time of birth, but postpartum care is more difficult to address.
- Pregnancy-related deaths spiked during the pandemic. The NCHS reported that maternal deaths peaked at 1,205 in 2021, with racial and ethnic minorities disproportionately harmed.
Resources
- Detailed Evaluation of Changes in Data Collection Methods — a CDC web page that explains changes in how maternal mortality data are collected.
- The Contemporary Challenge of Maternal Mortality in the U.S. — Boston University Professor Eugene Declercq’s overview presentation with many useful graphics.
- Guide to accurate and compassionate reporting on drug and alcohol use during pregnancy — advice from the Bixby Center for Global Reproductive Health a the University of California San Francisco.
