Maternal mortality statistics


Data collection methods are improving but still a challenge.



In the past 20 years while maternal mortality ratios (MMR) have fallen 48% in developed nations and 44% worldwide, the number of maternal deaths in the United States has actually doubled, from a low of 12/100,000 births in 1990 to 28/100,000 in 2013.1,2 At first glance, these numbers may look low, but these increases mean that the US mortality rate during that time has also increased, making it 1 of only 20 nations worldwide, 12 of which are in sub-Saharan Africa, where that has occurred. Currently, the United States has a higher MMR than nations such as Iran, Syria, Ukraine, and Jamaica.3

According to the Centers for Disease Control and Prevention (CDC), up to half of the maternal deaths in the United States should be preventable.4 If that is true, then we need to ask ourselves, why are these women dying? And who are they? Are there quantifiable differences in risk factors among women of different ages, races, ethnic or social groups or those who live in different locations? And because these answers are critical if our nation is to address the overall problem of maternal mortality effectively, intelligently and efficiently, what is the best way to obtain these data and be assured of their accuracy? 

Maternal mortality

The Word Health Organization (WHO) defines maternal mortality/maternal death as, “the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the duration and the site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management (direct or indirect obstetric death), but not from accidental or incidental causes.”2 In these instances, direct deaths are those caused by obstetric complications or any events that may arise from treatment or attempted treatment of these complications. Indirect deaths, on the other hand, are deaths that result from previously existing diseases or diseases that developed during pregnancy which are not caused by the pregnancy, but which are aggravated by it. The maternal mortality ratio is the number of maternal deaths per 100,000 live births.

Within these broad definitions of maternal mortality, several other distinctions are of value when collecting information about maternal death. For instance, a pregnancy-related death describes the death of a woman from any cause while she is pregnant or within 42 days of the termination of pregnancy. A later maternal death describes the death of a woman of either direct or indirect obstetric causes, more than 42 days but less than 1 year after pregnancy termination. The lifetime risk is the probability that a 15-year-old will eventually die of a maternal cause based on the existing risk of death for her country and the year.

Seeking to address the causes of maternal death is not a new effort. Currently, in the United States there are 2 national sources for maternal death information. The first is the National Center for Health Statistics (NCHS), which is part of the US Federal Statistical System and is the central resource for official vital statistics about health and health care in the United States. The NCHS determines the number of maternal deaths by using ICD-10 codes assigned according to information found on women’s death certificates.

The second source is the Pregnancy Mortality Surveillance System (PMSS-MM), which relies on death certificates that have either been marked with a check-box as being pregnancy-related or linked to a birth record or fetal death record registered in the year immediately preceding the maternal death. All marked certificates are reviewed by medical epidemiologists to determine the relation between any linked records, confirm a cause of death and then compile all the information into the overall mortality ratio.4

Each of these methods, however, does present challenges. States use different death forms and not all of them ask the same questions or identify a pregnancy-related death in the same way. Plus, there is no provision for recording other information that might add clarity to a specific case. Consequently, the number of maternal deaths is significantly under-reported. As the assessment processes have begun to evolve, the MMR has risen, leading to the question of whether numbers of maternal deaths are actually increasing or simply being more accurately reported.4

NEXT: Maternal Mortality Review Committees


Maternal Mortality Review Committees

For almost 100 years, many states and jurisdictions supported the creation of local Maternal Mortality Review Committees (MMRCs) whose jobs have been to bring greater clarity to the numbers and causes of maternal death nationwide. These committees may have uncovered valuable information but the ability to do comprehensive analyses across multiple agencies and populations was seriously impaired by the independence of the committees, the uncoordinated nature of data collected, and the different collection formats used. Some areas did not have resource committees at all, making it impossible to draw complete conclusions nationwide.

In 2015, a project called “Building U.S. Capacity to Review and Prevent Maternal Deaths” worked with the CDC and the Association of Maternal and Child Health Programs (AMCHP) to unite the efforts of the different MMRCs and collect data on maternal deaths in formats that are both consistent and comparable. This platform is called the Maternal Mortality Review Information Application (MMRIA, or “Maria”). The study started with the MMRCs in Colorado, Delaware, Georgia and Ohio. Data were entered by these states into the central Maternal Mortality Review Data System (MMRDS) which is held by the CDC. The focus of the centralized data collection was to “demonstrate the use of standardized review committee data for understanding the preventability, critical factors that contribute to death, and best opportunities for reducing pregnancy-related deaths, rather than trends in mortality over time.”4

When a case of possible maternal death is identified, the MMRCS utilizes the services of a variety of health professionals (from areas such as public health, obstetrics, gynecology, nursing, midwifery, forensic pathology, mental and behavioral health, social workers, patient advocates) and a wide range of records - medical and non-medical, ante- and post-partum; informant interviews, social service records, etc. -  to build a narrative for each case that covers all aspects of the patient’s personal experience throughout her pregnancy, up to her death. When complete, each case is analyzed by committee to determine:

  • Was the death pregnancy-related? The patient’s cause of death and any relation to pregnancy is assigned to 1 of 4 categories:  Pregnancy-Related, Pregnancy-Associated but NOT Related, Not Pregnancy-Related or Associated, Unable to Determine if Pregnancy-Related or Associated (Table 1).
  • What was the cause of death? This information is obtained from the PMSS-MM and acts as an informational link between the PMSS-MM records and the MMRIA, promoting consistency between the systems.
  • Was the death preventable? If the committee determines that reasonable changes in any 1 of 5 areas - to the patient, provider, community, facility or systems of care - might have prevented the death, then the death is considered to be preventable. The committee also has the option of documenting the degree of preventability assigned, from “none” through 4 levels, to “strong.”
  • What were the critical contributing factors to the death? Contributing factors are assigned to 1 of 5 areas – again, to the patient, provider, community, facility or systems of care. Each factor is assigned to an explanatory class category, such as delays, adherence, lack of knowledge, etc., with a concise description of the specific factor.
  • What are the recommendations and actions that address the contributing factors? Any actions or recommendations that might have prevented or contributed to the prevention of this specific death are identified, with information about who should initiate action, when the action should be initiated, and a description of the action itself.
  • What is the anticipated impact of those actions if implemented? The MMRCs assign a specific level of prevention to each recommendation to determine whether an action would prevent the contributing factor before it occurred (primary prevention), reduce the impact of a contributing factor that has occurred (secondary prevention), or reduce the impact or progression of an ongoing contributing factor (tertiary prevention). The recommendations are then prioritized, with those supporting primary prevention, usually, as the higher priority.


What comes next

In 2016 over 30 states were contacted to define ways to integrate them into the MMRDS and identify their individual data needs. Because of those interactions, project staff have begun to add other information to the system, such as details about suicide, mental health criteria, drug abuse, and partner abuse. Partnerships with Violent Death Reporting systems in different states have also been initiated. The addition of information about these challenging issues placed in the context of pregnancy will provide an even more complete image of what is killing our nation’s mothers and, hopefully, guide us in our search for tools and techniques to reduce the number of these unfortunate deaths. 



1. MacDorman, Marian F. PhD; Declercq, Eugene PhD; Thoma, Marie E. PhD. Trends in Maternal Mortality by Sociodemographic Characteristics and Cause of Death in 27 States and the District of Columbia. Obstetrics & Gynecology: May 2017 - Volume 129 - Issue 5 - p 811–818 doi: 10.1097/AOG.0000000000001968

2. Trends in maternal mortality: 1990 to 2015: estimates by WHO, UNICEF, UNFPA, World Bank Group and the United Nations Population Division. Geneva: World Health Organization; 2015.

3. Kassebaum NJ, Bertozzi-Villa A, Coggeshall MS, et al. Global, regional, and national levels and causes of maternal mortality during 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013. 13;384(9947):980-1004. doi: 10.1016/S0140-6736(14)60696-6. Epub 2014 May 2. Erratum in: Lancet. 2014 Sep 13;384(9947):956. PMID:24797575

4. Maternal Mortality CDC 2017. Report from Maternal Mortality Review Committees: A View into Their Critical Role.

  Accessed December 20, 2017

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