The maternal mortality rate in 48 states and the District of Columbia increased by 26.6% between 2000 and 2014—from 18.8 to 23.8 per 100,000 live births—according to a recent study. Only California, which was analyzed separately, showed a decline in maternal deaths between 2003 and 2014. By contrast, Texas—also analyzed separately—saw its rate double between 2010 and 2012, although the reasons for this spike are unclear.
In calculating these rates, the researchers endeavored to adjust for the addition in 2003 of a question about pregnancy to the U.S. standard death certificate. Using check boxes, the question asks whether female decedents were pregnant at the time of death or within 42 days of death or between 43 days and one year before death.
Because this question wasn't immediately or uniformly adopted by the states, it has been difficult to extrapolate a national maternal mortality rate. Indeed, the United States has not published an official maternal mortality rate since 2007. Complicating the statistical analysis is the fact that maternal mortality is uncommon, accounting for only 396 U.S. deaths in 2000 and 856 in 2014. To adjust for these factors, the researchers examined data from the National Center for Health Statistics and the Centers for Disease Control and Prevention's CDC WONDER online database, and also corrected for differences in the timing of each state's adoption of the pregnancy question. Some states added it immediately in 2003 while others hadn't done so as late as January 1, 2014—the study's cutoff date.
Exactly why the maternal mortality rate has increased in all states but one remains unclear. “Various potential interrelated causes have been discussed,” says Kathleen R. Simpson, editor-in-chief of MCN: the American Journal of Maternal/Child Nursing. “These include the increased age of women giving birth, an increase in maternal morbidities—preeclampsia, diabetes, and obesity—and more interventions, such as induction of labor and cesarean birth, which have associated risks.” It's also possible that U.S. rates in the early 2000s were higher than reported, the researchers suggest.
The most puzzling finding has been the doubling of the maternal mortality rate in Texas between 2010 and 2012. The state adopted the pregnancy question in 2006—long before the spike—and also measured a relatively small increase in the maternal death rate between 2000 (17.7) and 2010 (18.6). To understand what occurred, the researchers recommend additional study of the Texas data by race and ethnicity and with detailed examination of causes of death.
As for California's success, the researchers point to the initiation of a statewide review in 2006 and a joint effort with the California Maternal Quality Care Collaborative to explore and address the primary causes of maternal death, among them obstetric hemorrhage and preeclampsia.
California's approach, says Simpson, “has been adopted by the Alliance for Innovation on Maternal Health, a partnership of key stakeholders, which has developed a series of maternal safety bundles to cover essential aspects of care for pregnancy and childbirth. Wide dissemination of the bundles with prompt adoption and integration into clinical practice by all other states and the District of Columbia may be one of the key strategies in finally addressing maternal morbidity and mortality in the United States.”—Dalia Sofer
MacDorman MF, et al. Obstet Gynecol 2016 128 3 447–55