Maternal Mortality Rates on the Rise in Most US States

Diana Phillips

August 08, 2016

The United States appears to have fallen far short of the United Nations Millennium Development Goal that targeted a 75% reduction in maternal mortality by 2015.

According to new research published in the September issue of Obstetrics & Gynecology, the estimated maternal mortality rate for nearly all of the 48 states included in the analysis increased from 2000 to 2014.

California alone showed a declining trend, consistent with international maternal mortality data, Marian F. MacDorman, PhD, from the Maryland Population Research Center, University of Maryland, College Park, and colleagues report.

A second study reported in the same issue indicates that pregnancy-associated deaths due to violence are three times more likely than deaths associated with the leading pregnancy-related causes of maternal mortality.

Although much of the reported increase in maternal mortality rates from 2000 to 2014 "was the result of improved ascertainment of maternal deaths," the authors write, combined data for 48 states and the District of Columbia showed a 26.6% increase in the estimated maternal mortality rate, from 18.8 in 2000 to 23.8 in 2014. "Clearly at a time when the World Health Organization reports that 157 of 183 countries studied had decreases in maternal mortality between 2000 and 2013, the U.S. maternal mortality rate is moving in the wrong direction," they state.

These updated rates are significantly larger than those from the Centers for Disease Control and Prevention (CDC) that were published in the January 2015 issue of Obstetrics & Gynecology, editor-in-chief Nancy C. Chescheir, MD, professor and director of prenatal diagnosis at the University of North Carolina, Chapel Hill, writes in an associated editorial. The earlier data, reported previously by Medscape Medical News, "showed that there had been a steady increase from 9.1 per 100,000 live births between 1987 and 1990 to 16.0 per 100,000 live births from 2006 to 2010."

The updated statistics come from a new analytical model that compensates for deficits in the collection of maternal mortality statistics, particularly with the addition in 2003 of a pregnancy question to the US standard death certificate. Although the question — which includes checkboxes to indicate whether female decedents were not pregnant at the time of death, pregnant at the time of death, not pregnant at the time of death but pregnant within 42 days of death, not pregnant at the time of death but pregnant from 43 days to 1 year before death, or of unknown pregnancy status — was designed to improve the accuracy of maternal mortality estimates, the question has been inconsistently adopted by individual states.

"[I]n any given data year, some states were using the U.S. standard question, others were using questions incompatible with the U.S. standard, and still others had no pregnancy question on their death certificates," the authors write. As a result, the United States has not published an official maternal mortality rate since 2007, an "international embarrassment," according to the authors, stemming from chronic underfunding of state and national vital statistics systems and contributing to a dearth of comparative data for international data repositories and impeding the assessment of progress toward improvement goals.

In an effort to provide an overview of US maternal mortality rates from 2000 to 2014, the study authors developed and tested methods for trend analysis of maternal mortality data, taking into account state revision dates and different question formats, and they developed a correction procedure to adjust unrevised data to be comparable to revised data.

Using maternal mortality data derived from publically available mortality data files from the National Center for Health Statistics and through the CDC, the researchers computed mortality rates per 100,000 live births to model trends over time.

Because maternal death is rare, states were grouped for trend analyses based on certain shared characteristics regarding the timing or nature of their inclusion of the standard pregnancy question. California was the exception because it was the only state that revised its death certificate with a pregnancy question inconsistent with the US standard. The California trend analysis combined maternal and late maternal (within 1 year of pregnancy) deaths. The estimation of maternal mortality excluded both California and Texas — "California because it does not provide comparable data and Texas as a result of uncertainty regarding recent trends the collection of more accurate maternal mortality statistics," the authors write.

The modeled maternal mortality rates for California decreased from 21.5 in 2003 to 15.1 in 2014, reflecting a 0.58-unit decrease in the combined maternal and late maternal mortality rate per year based on 1190 maternal deaths and 6,356,032 live births, according to the authors, who attribute the decrease to successful public health and private efforts with the California Maternal Quality Care Collaborative.

Adjusted maternal mortality rates for Texas show only a modest increase from 2000 to 2010, from a rate of 17.7 in 2000 to 18.6 in 2010. "[H]owever, after 2010, the reported maternal mortality rate for Texas doubled within a 2-year period to levels not seen in other U.S. states," the authors write.

"[H]ad the National Center for Health Statistics and the Texas vital statistics office both been publishing annual maternal mortality rates, the unusual findings from Texas for 2011–2014 would certainly have been investigated much sooner and in greater detail," the authors stress. "The lack of publication of U.S. maternal mortality data since 2007 has also meant that these data have received a lesser degree of scrutiny and quality control when compared with published vital statistics measures such as infant mortality."

The fact that the maternal mortality rate for 48 states and Washington, DC, during the study period "was higher than previously reported, is increasing, and places the United States far behind other industrialized nations" points to a need to improve maternity care and focus attention on efforts targeting the prevention of maternal deaths, the authors write. "Accurate measurement of maternal mortality is an essential first step in prevention efforts, because it can identify at-risk populations and measure the progress of prevention programs."

Findings from another report published in the same issue of the journal suggest that prevention efforts should also include an increased understanding of all causes of maternal mortality, including violence.

In a retrospective, multicohort, ecologic study of females of reproductive age in Illinois between 2002 and 2011, Abigail R. Koch, MA, from the Center for Research on Women and Gender at the University of Illinois at Chicago, and colleagues reviewed Illinois Department of Public Health maternal mortality data and vital records data to identify pregnancy-associated deaths and their causes. Of 636 pregnancy-associated deaths, 82 (13%) were the result of homicide (5.0 [95% confidence interval (CI), 4.0 - 6.2]/100,000 live births).

The researchers determined that deaths from all violent causes, including motor vehicle accidents, homicide, suicide, and substance abuse, occurred at a rate of about 15 per 100,000 live births, substantially higher than deaths associated with the four leading pregnancy-related causes of maternal mortality (hemorrhage, embolic disease, hypertensive disease, and sepsis), which occurred at a rate of about 4.5 per 100,000 live births.

Looking at homicide specifically, in a comparison with the homicide rate among females in the same age range not associated with pregnancy, pregnant and postpartum females aged 10 to 29 years were twice as likely to die of homicide than their nonpregnant or postpartum counterparts (relative risk, 2.20 [95% CI, 1.70 - 2.85]). The risk for homicide among pregnant and postpartum females was higher among non-Hispanic black and Hispanic women, the authors report.

"Although all violence against females must be addressed, we recommend that state maternal mortality review committees, in addition to reviewing deaths resulting from obstetric and clinical causes, should conduct in-depth reviews of pregnancy-associated homicides and other violent deaths," the authors write. "It is only when we assess factors that increase females' risk of homicide during pregnancy and the postpartum period that we can identify populations and targets amenable to intervention."

In her editorial, Dr Chescheir identifies several strategies to prevent deaths due to violence in pregnant and postpartum women:

  • Accept that the rising rate of maternal deaths is real and clinicians have important roles to play in preventing them.

  • Incorporate validated screening tools for risk for death due to violence into clinical practice in prenatal, emergency, and gynecology settings.

  • Provide referral resources to women identified as at-risk.

  • Participate in advocacy work for women's health and safety within the healthcare system and the broader community.

"Most of the time, I think of women in terms like 'strong,' 'able,' 'adaptable,' and 'powerful.' These two articles remind me that pregnant women are also vulnerable," Dr Chescheir writes. "Our very difficult job is to provide care that respects this full spectrum: to further empower women as partners in their care and to try to protect them at the same time."

The authors of both studies and Dr Chescheir have disclosed no relevant financial relationships.

Obstet Gynecol. 2016;128:427-428, 440-446, 447-455.

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