FROM OBSTETRICS & GYNECOLOGY
Better surveillance could be responsible for increased rates of U.S. maternal mortality, a sign that previous estimates were too low, according to a new study.
For more than 2 decades, rates of maternal deaths have increased significantly, climbing from 7.55 per 100,000 live births in 1993 to 9.88 in 1999, and rising again to 21.5 in 2014. This means the relative risk of maternal death between 2014 and 1993 was 2.84, while it was 2.17 between 2014 and 1999.
Although rising rates of obesity and other chronic conditions are often theorized as possible factors in the spiking maternal death rates K.S. Joseph, MD, PhD , of the University of British Columbia, Vancouver, and his colleagues suggest the more likely causes are improved maternal death surveillance and changes in how these deaths are coded.
This conclusion is based on a retrospective cohort analysis of maternal deaths and live births from 1993-2014 as recorded in the National Center for Health Statistics and the Wide-Ranging Online Data for Epidemiologic Research files of the Centers for Disease Control and Prevention (Obstet Gynecol 2017;129:91-100).
Surveillance and reporting changes have been implemented across the country over the last few decades. During the 1990s, some states began including a separate question regarding pregnancy on death certificates. Starting in 2003, pregnancy was added to the standardized checklist of causes of death on certificates used nationwide, although state-by-state implementation has varied. In addition, in 1999, ICD-10 codes for underlying causes of death were introduced, including O96 and O97 for late maternal deaths, O26.8 for specified pregnancy-related conditions, and O99 for other maternal diseases classifiable elsewhere.
When Dr. Joseph and his colleagues excluded from their analysis maternal deaths coded according to the new ICD-10 codes primarily related to renal disease and other maternal diseases classifiable elsewhere, the increase between 1999 and 2014 was erased, dropping the relative risk to 1.09 (95% CI, 0.94-1.27).
Adjustment for improvements in surveillance also wiped out the temporal increase in maternal mortality rates for a relative risk of 1.06 for 2013 compared to 1993 (95% CI, 0.90-1.25).
“Reports of temporal increases in maternal mortality rates in the United States have led to shock and soul-searching by clinicians,” the investigators wrote. “In fact, maternal deaths from conditions historically associated with high case fatality rates including preeclampsia, eclampsia, complications of labor and delivery, antepartum and postpartum hemorrhage, and abortion either declined substantially or remained stable between 1999 and 2014.”
The investigators did not report having any potential conflicts of interest.
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