Am J Obstet Gynecol

Is the high U.S. maternal death rate due to bad data?

March 18, 2024

Data classification errors may have inflated U.S. maternal death rates for two decades, according to a study published in the American Journal of Obstetrics & Gynecology. Instead of the maternal death rate increasing by 144% since 1999, this new research found that there was only a 2% increase since that time.

Starting in 2003, a pregnancy checkbox was included in national death certificates. Researchers found that this box was checked for many deaths unrelated to either pregnancy or childbirth, resulting in misclassifications. Instead, researchers posit that identifying maternal deaths by requiring mention of pregnancy among the multiple causes of death shows lower, stable maternal mortality rates and declines in maternal deaths from direct obstetrical causes.

• Using the National Vital Statistics System methodology, maternal deaths increased by 144% from 9.65 in 1999-2002 (n=1550) to 23.6 per 100,000 live births in 2018-2021 (n=3489), with increases occurring among all race and ethnicity groups.
• Further analysis, however, revealed that the rise was actually due to indirect obstetrical death—death not caused by pregnancy or childbirth but which happened while pregnant or was exacerbated by pregnancy.
• Direct obstetrical deaths increased from 8.41 in 1999-2002 to 14.1 per 100,000 live births in 2018-2021, whereas indirect obstetrical deaths increased from 1.24 to 9.41 per 100,000 live births.
• Researchers found that 38% of direct obstetrical deaths and 87% of indirect obstetrical deaths in 2018-2021 were identified because of a positive pregnancy checkbox; this checkbox was associated with increases in less specific and incidental causes of death.
• Under the researchers' alternative formulation, the maternal mortality rate was only 10.2 in 1999-2002 and 10.4 per 100,000 live births in 2018-2021; deaths from direct obstetrical causes decreased from 7.05 to 5.82 per 100,000 live births.
• Deaths due to preeclampsia, eclampsia, postpartum hemorrhage, puerperal sepsis, venous complications, and embolism decreased, whereas deaths due to adherent placenta, renal and unspecified causes, cardiomyopathy, and preexisting hypertension increased.
• Maternal mortality increased among non-Hispanic White women and decreased among non-Hispanic Black and Hispanic women. However, rates were still disproportionately higher among non-Hispanic Black women, with large disparities evident in several causes of death (eg, cardiomyopathy).

Source:

Joseph KS, et al. (2024, February 29). Am J Obstet Gynecol. Maternal mortality in the United States: are the high and rising rates due to changes in obstetrical factors, maternal medical conditions, or maternal mortality surveillance? https://pubmed.ncbi.nlm.nih.gov/38480029/