High and rising U.S. maternal mortality rates are due to flawed data, study shows

A new study has found that high and rising rates of maternal mortality in the United States are due to flawed data.

The maternal mortality crisis in the U.S. has shown high rates of maternal deaths compared to other countries – but the study, published Wednesday in the American Journal of Obstetrics & Gynecology, found that data may have been classified incorrectly for two decades.

The number of women dying after giving birth has been concerning and raised questions about care in the U.S. While past estimates show the maternal mortality rate has more than doubled in the last two decades, the study found that it has remained steady.

In 2003, the National Center for Health Statistics (NCHS) recommended that “pregnancy” be added to a checklist on a person’s death certificate as a way to track maternal deaths.

While there was a rapid increase in maternal mortality rates after the checklist was updated, it resulted in “some egregious errors,” including hundreds of people above the age of 70 being listed as pregnant at the time of death or shortly before their death. Deaths from other causes would be considered maternal mortality if the pregnant box was checked.

NCHS later clarified that only women 15 to 44 should be in the category, hoping it would minimize errors going forward. Women over 44 could be counted if there was a specific cause of death tied to a pregnancy. Otherwise, the agency counted women of birthing age the same as before.

Researchers found that despite the changes, reports still show increased maternal mortality rates or an increase in misclassified maternal deaths.

When death certificates mention pregnancy among multiple causes of death, researchers found that maternal mortality rates lower and stabilize over time.

The study noted that “large racial and ethnic disparities in maternal mortality persist.” Maternal mortality rates were disproportionately higher among Black women, with large disparities evident in causes of death like ectopic pregnancies, hypertensive disorders, embolism, cardiomyopathy and other cardiovascular diseases, researchers found.  

Using the new method of tracking, researchers found that from 1999 to 2002, maternal mortality rates in the U.S. were 10.2 per 100,000 live births. From 2018 to 2021, it was 10.4, a 2 percent increase.