Is US maternal mortality rising? Maybe not.

Tombstone Mother

I’ve been writing about the issue of US maternal mortality for years, and for years I’ve argued that most of the supposed increase is a result of improved reporting of maternal deaths, not more deaths.

That view was confirmed by the recent paper Is the United States Maternal Mortality Rate Increasing? Disentangling trends from measurement issues by MacDorman et al.

[pullquote align=”right” cite=”” link=”” color=”” class=”” size=””]”The overall picture is not consistent with any serious deterioration in maternal health or maternal health services in the United States.”[/pullquote]

Studies based on data from the 1980s and 1990s identified significant underreporting of maternal deaths… To improve ascertainment, a pregnancy question was added to the 2003 revision of the U.S. standard death certificate…

However, there were delays in states’ adoption of the revised death certificate … 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…

While raw data suggested that US maternal mortality had more than doubled since 2000, MacDorman and colleagues found that the real increase was only 26.4%, a much smaller increase, but an increase nonetheless.

Now a new paper, Factors Underlying the Temporal Increase in Maternal Mortality in the United States by Joseph et al., questions even the smaller increase.

The authors note:

Recent publications on global trends in maternal mortality have reported substantial increases in maternal deaths in the United States … The maternal mortality ratio in the United States in 2013 was higher than that in Azerbaijan, Iran, Kazakhstan, Libya, Saudi Arabia, and Uruguay (among others)… Such reports have led to considerable dismay in the United States and pleas for prompt clinical action to reduce maternal deaths.

It is difficult to reconcile the maternal mortality ratios in the United States with the lower estimates of these rates in less industrialized countries. Several explanations have been offered to explain the observed temporal increase in maternal mortality including an increase in chronic diseases among reproductive-aged women (especially obesity) and increasing rates of cesarean delivery. However, an alternative narrative, which views the rising rates of maternal mortality in the United States as an artifact of improved surveillance, implicates several different changes in maternal death surveillance …

The authors analyzed changes in both the overall rate of maternal mortality from 1999-2014 and cause specific mortality rates. They found that deaths from traditional causes actually DECLINED while deaths in new categories increased substantially.

Maternal mortality ratios (excluding late maternal deaths) increased from 9.88 in 1999 to 21.5 per 100,000 live births in 2014 (RR 2.17, 95% CI 1.93–2.45). However, maternal deaths resulting from complications of labor and delivery declined significantly over the same period (RR 0.43, 95% CI 0.27–0.68). There was no significant change in maternal deaths resulting from abortive outcomes (O00–O07), edema, proteinuria and hypertensive disorders, maternal care related to the fetus and amniotic cavity, and complications predominantly related to the puerperium. However, deaths resulting from other maternal disorders predominantly related to pregnancy and deaths resulting from other obstetric problems not elsewhere classified increased substantially between 1999 and 2014 (RR 10.0, 95% CI 6.85–14.7 and 5.88, 95% CI 4.38–7.89).

The difference was even more pronounced for late maternal deaths, many of which were not captured before the changes in reporting requirements;

Late maternal deaths, that is, obstetric deaths greater than 42 days and less than 1 year after delivery and deaths from sequelae of obstetric causes, increased from 0.38 in 1999 to 6.69 per 100,000 live births in 2014 (RR 17.7, 95% CI 10.5–29.7). Exclusion of codes O26.8 (other specified pregnancy-related conditions) and O99 (other maternal diseases classifiable elsewhere but complicating pregnancy, childbirth, and the puerperium) and late maternal deaths (O96 and O97) abolished the temporal increase in these maternal mortality ratios.

The authors explain:

Our study suggests that the reported substantial increase in maternal mortality in the United States between 1993 and 2014 was likely a consequence of improvements in maternal death surveillance and changes in the coding of maternal deaths. Regression adjustment for the separate pregnancy question on death certificates, ICD-10 codes, and the standard pregnancy checkbox on death certificates eliminated the increase in maternal mortality rates between 1993 and 2014. Exclusion of maternal deaths associated with the four new ICD-10 codes that identified late maternal deaths (O96, O97), other specified pregnancy-related conditions (O26.8), and other maternal diseases classifiable elsewhere (O99) also abolished the temporal increase in maternal mortality between 1999 and 2014.

Most other countries have not instituted new maternal mortality guidelines. Therefore it is hardly surprising that US maternal mortality ranking has dropped in relation to other countries that aren’t recording all maternal deaths.

The authors conclude:

Although there may have been some increase in maternal deaths resulting from chronic diseases (such as diseases of the circulatory system, diabetes, and liver disease) and definite reductions in maternal death resulting from obstetric causes (such as preeclampsia, eclampsia, and complications of labor and delivery), the overall picture is not consistent with any serious deterioration in maternal health or maternal health services in the United States.

Which is what I have been saying all along.