Pregnancy-related deaths more frequent than reported

A new study highlights why a broader definition of maternal mortality raises public health challenges.

By Stephanie Stapleton, amednews staff. April 9, 2001.

Washington -- Maternal mortality in the United States is measured in single digits.

However, a study published in the March 21 JAMA offered a new round of evidence that the number of women who die from pregnancy-related illnesses or episodes is chronically undercounted. Even more disturbing, the study's data, collected in Maryland, conclude that the primary cause of these deaths was homicide.

"Clearly, pregnancy is a lot safer than it was 50 years ago, but not as safe as we would expect. Many deaths are not counted," said Isabelle L. Horon, DrPH, director of the Maryland Dept. of Health and Mental Hygiene Vital Statistics Administration in Baltimore, and lead author of the JAMA article.

Uncovering the number of homicides, which accounted for 20% of all pregnancy-related deaths in the study, was not the goal of her research, she added. But it was a surprising finding that raises important public health policy questions. "Until we know what is a problem, we don't know how to address it," she said. "[Identification] is the first step."

When women who are pregnant or who have had a recent pregnancy die, it is devastating to family, friends and communities. The collection of accurate information about these deaths is critical in developing preventive strategies, according to the article. And the first step is gaining a more clear picture of the magnitude of pregnancy-associated mortality so that interventions can be formulated.

In 1993, for instance, there were three maternal deaths reported in Maryland. "You look at that number and think 'three deaths -- big deal,' " said Dr. Horon. However, researchers accumulated data indicating that the number was actually substantially higher and the causes significantly broader.

Why the disconnect?

First, death records are an important source of data on pregnancy mortality, according to the study. But there are limitations to using them to identify all deaths associated with pregnancy. When completing death records, doctors fail to report that the woman was pregnant or had a recent pregnancy in 50% or more of these cases. The result is a potential misclassification of the underlying cause.

"It's not purposeful underreporting," explained Thomas J. Benedetti, MD, a professor at the University of Washington School of Medicine and director of its perinatal medicine division in the Dept. of Obstetrics and Gynecology. "The psychological trauma of what's just happened to you and your patient makes it difficult." Dr. Benedetti conducted one of the first studies of maternal mortality surveillance 20 years ago and found the underreporting rate to be as high as 50% over a five- or six-year period.

But the reporting system itself also adds to the challenge. Only 17 states and New York City currently have a pregnancy check box or ask about pregnancy status on death certificates. As a result, more detailed surveillance requires labor-intensive linkages between deaths and births, as well as other sources of epidemiologic information.

Dr. Horon and colleagues used such "enhanced surveillance" methods to track the number and causes of pregnancy-associated deaths in Maryland between 1993 and 1998. They also relied on an expanded version of the World Health Organization's definition of maternal death. WHO's statistics focus on the deaths of women while pregnant or within 42 days of termination of pregnancy, from causes related to or aggravated by the pregnancy or its management. Thus the WHO classification includes hemorrhage, pregnancy-induced hypertension and embolism. It excludes accidents, homicides or even suicides that occurred up to 365 days after the pregnancy.

"These causes are not counted in maternity mortality rates even though pregnancy might be the driving force behind them," Dr. Horon said. Therefore, the Maryland researchers used the term "pregnancy-associated death," introduced by the Centers for Disease Control and Prevention in collaboration with the Maternal Mortality Special Interest Group of the American College of Obstetricians and Gynecologists. It takes a broader view, encompassing all deaths from any cause during pregnancy or within one calendar year of delivery or pregnancy termination.

The researchers were able to identify 247 pregnancy-associated deaths. Of those, 27% were identified from death certificate cause-of-death information, 70% through comparisons of death records with birth and fetal death records, and 47% through review of medical examiner records. (In some cases, a single death may have been determined from more than one surveillance method.) Homicide was the leading cause and cardiovascular disorders were the second.

"The findings of this article also suggest that maternal mortality review committees should investigate homicides occurring during pregnancy and in the postpartum period to determine potential relationships between these events," the researchers wrote. "For example, a homicide resulting from domestic violence may be related to the stress of pregnancy. Similarly, a suicide soon after delivery may result from postpartum depression. By broadening pregnancy mortality to include all possible causes, factors previously neglected may assume increased importance in prenatal and postpartum care."

The ultimate goal, of course, is to bring the instances of maternal mortality to an "irreducible number," said Dr. Benedetti. To reach that number, "we have to know what it is and have to develop accuracy," he added.

Attention also must be paid to ensuring that improvements in reporting are made in ways that also have positive consequences in correcting the underlying problems, he said.