Is the US over-counting maternal deaths?

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The mainstream media is filled with stories claiming that the US maternal death rate has risen dramatically since 1990. The latest effort comes from USA Today, Hospitals know how to protect mothers. They just aren’t doing it.

The vast majority of women in America give birth without incident. But each year, more than 50,000 are severely injured. About 700 mothers die. The best estimates say that half of these deaths could be prevented and half the injuries reduced or eliminated with better care.

Instead, the U.S. continues to watch other countries improve as it falls behind. Today, this is the most dangerous place in the developed world to give birth.

They include a helpful chart:


There’s just one problem and it’s a big one: no one knows if those measurements of US maternal mortality are accurate. Indeed, there’s a growing body of evidence that the US is over-counting maternal deaths.

[pullquote align=”right” cite=”” link=”” color=”” class=”” size=””]There’s a growing body of evidence that the US is over-counting maternal deaths.[/pullquote]

In the 1990’s it was recognized that the US was failing to capture all maternal deaths. As a result, the US death certificate was changed twice (1999 and 2003) to add specific questions to determine the pregnancy status of the deceased. But death certificates are prepared by individual states and each changed their deaths certificates at different times.

As MacDorman et al. explained in 2016 in Is the United States Maternal Mortality Rate Increasing? Disentangling trends from measurement issues:

To improve ascertainment, a pregnancy question was added to the 2003 revision of the U.S. standard death certificate. The question has several checkboxes to ascertain whether female decedents were: Not pregnant within past year; pregnant at time of death; not pregnant, but pregnant within 42 days of death; not pregnant, but pregnant 43 days to 1 year before death; or unknown if pregnant within the past year…

However, there were delays in states’ adoption of the revised death certificate, and thus the new pregnancy question. In addition, some states had pregnancy questions that were inconsistent with the U.S. standard. This created a situation where, in 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.

Due in part to the difficulties in disentangling these effects, the United States has not published an official maternal mortality rate since 2007 …

MacDorman et al. used statistical estimates to correct for the differences. While raw data suggested that US maternal mortality had more than doubled since 2000, they found that the real increase was only 26.4%, a much smaller increase, but an increase nonetheless.

But even this increase may not be real. Suspicion initially fell on the data from Texas that had shown a massive increase in maternal mortality:


Reproductive rights advocates seized on the data to argue that Texas’ efforts to roll back access to reproductive care had led to the increase, but a closer look revealed that the state had dramatically over-counted maternal deaths.

In Identifying Maternal Deaths in Texas Using an Enhanced Method, 2012, Baeva et al. found:

Fifty-six maternal deaths were confirmed to have occurred during pregnancy or within 42 days postpartum. Using our enhanced method, the 2012 maternal mortality ratio for Texas was 14.6 maternal deaths per 100,000 live births, less than half that obtained using the standard method (n5147). Approximately half (50.3%) of obstetric-coded deaths showed no evidence of pregnancy within 42 days, and a large majority of these incorrectly indicated pregnancy at the time of death.

How did this happen?

In Texas, unintentional user error in reporting pregnancy status may be responsible. Texas’ current electronic death registration system displays pregnancy status options as a dropdown list. The “pregnant at the time of death” option is directly below the “not pregnant within the past year” option; this could have led to erroneous selection and could explain why pregnancy at the time of death was reported for nearly 76% (n556) of the 74 obstetric-coded deaths with no evidence of pregnancy on review.

The situation in Texas is not unique.

MacDorman and Declercq writing in the June 2018 issue of Birth: Issues in Perinatal Care (published on behalf of Lamaze International) note:

For example, a recent Centers for Disease Control and Prevention (CDC) report from maternal mortality review committees in four states found that 15% (97/650) of reported maternal deaths were not maternal deaths at all, since the women involved were confirmed to be not pregnant or postpartum within 1 year of death. The same study also found that the checkbox identified cases, particularly during pregnancy or late postpartum, that were identified only because of the checkbox, and with no other evidence that the case was a maternal death. Thus, the errors of overcounting were predominantly because of errors in the pregnancy checkbox.

This is a serious error:

The problems in reporting of pregnancy status are compounded by United States coding rules that code every death with the pregnancy or postpartum checkbox checked to maternal causes, regardless of what is written in the cause-of-death section. The only exception is for external causes of injury (ie, accident, suicide, or homicide) which are coded to non-maternal causes. This coding scheme makes the checkbox information essentially the sole factor in deciding whether a death is maternal or nonmaternal. For example, right now, if “sunburn” is written as the cause of death, and if the pregnancy or postpartum checkbox is checked, United States coding rules code this as a maternal death. This coding is clearly not in keeping with the spirit of the World Health Organization maternal mortality definition of maternal death …

They conclude:

Given concerns about overreporting with the pregnancy checkbox, it is illogical to continue to use it as the sole means of identifying maternal deaths. The National Center for Health Statistics (the agency responsible for collecting and disseminating NVSS data) should undertake a systematic evaluation of current coding methods for maternal deaths, and develop scientifically defensible alternative methods, which are compatible with international standards.

There a scientific aphorism that suggests extraordinary claims require extraordinary evidence. In this case there are two extraordinary claims: since 1999 US maternal mortality has risen dramatically and the US now has the highest maternal mortality in the industrialized world.

The evidence, far from being extraordinary, is incredibly inaccurate because of over-counting.

That does NOT mean that our efforts to reduce maternal mortality should flag. No one is questioning the massive gap in maternal outcomes between black and white women and that must be reduced. But it does mean that the hand wringing over the rise in US maternal mortality might be both premature and overblown.