How do we know the global profile of maternal mortality and morbidity?
In The Lancet Maternal Health Series, Wendy Graham et al, Dorothy Shaw et al, and Margaret Kruk et al highlight why it is important to measure maternal health, how maternal health is measured, and what is needed to further improve surveillance.
Why is it important to measure maternal health?
There are several reasons to collect information on women’s health1. These are:
- To record the levels of particular health outcomes for women so we can set priorities and monitor trends;
- To identify the characteristics of, and reasons for, particular health outcomes so we can understand risk factors and intervene where possible; and
- To monitor and evaluate the effectiveness of interventions aimed at influencing and improving women’s health outcomes, and to drive practice improvement
The challenge is to create information systems that are feasible (low burden and low cost), timely, reliable, and actionable. Better measurement and coding of maternal mortality and morbidity, including direct and indirect causes and risk factors, is needed to set implementation priorities, to guide intervention research, and improve quality of care, particularly for women and babies at greatest risk. The measurement of maternal morbidity is particularly important as, for every woman who dies of a pregnancy related death, 20–30 women experience acute or chronic morbidity2. We also need to measure mental health and the positive aspects of maternal health and well-being.
How do we measure maternal morbidity and mortality?
Categorisation of causes of maternal mortality and morbidity have changed over time, which has meant that the data captured on maternal mortality and morbidity have also altered, and in some cases, improved over time3. Maternal mortality is defined and categorised in several ways (see Box 1). Maternal morbidity is arguably harder to define as a result of the range of conditions that can affect women’s physical, mental, or sexual health, and their ability to function in society. Consequently, there has been much debate about how best to measure maternal morbidity. The World Health Organization have built on existing work to develop standardised definitions, and have identified 121 diagnostic categories, illustrating the diversity of the morbidity burden1. Despite this, there is still much work for future researchers to do to ensure global consistency with definitions and classification
|Maternal Mortality Definitions4|
|Maternal death is defined as a death while pregnant, or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management but not from accidental or incidental causes. These can be subdivided into direct obstetric deaths and indirect obstetric deaths.|
|Late maternal death is defined as a death from direct or indirect obstetric causes, more than 42 days, but less than one year, after termination of pregnancy.|
|Pregnancy-related death is defined as a death while pregnant or within 42 days of termination of pregnancy, irrespective of the cause of death.|
Direct obstetric deaths result from obstetric complications of the pregnancy state such as obstetric haemorrhage or eclampsia, which would not occur outside pregnancy or the puerperium. Indirect obstetric death results from existing disease or disease that developed during the pregnancy which was not a result of direct obstetric causes, but which was aggravated by the physiologic effects of pregnancy, such as cardiac conditions aggravated by pregnancy.
|Maternal Morbidity Definitions5|
|Maternal morbidity and associated disability: Any health condition attributed to and/or complicating pregnancy and childbirth that has a negative impact on the woman’s wellbeing and/or functioning.|
|Maternal near miss: A woman who nearly died but survived a complication that occurred during pregnancy, childbirth or within 42 days of termination of pregnancy. Signs of organ dysfunction that follow life-threatening conditions are used to identify maternal near-misses, and a set of near-miss indicators enables assessments of the quality of care provided to pregnant women.|
Different indicators are used to measure maternal deaths (see Box 2) – and some countries collect this data more accurately than others. Indicators of maternal morbidity should ideally use epidemiologic measures such as incidence rates, incidence risks and prevalence. These measures necessitate choosing, for example, whether to calculate incidence among those still at risk (incidence rate) or among the initial population entering the risk period (incidence risk) and whether to measure morbidity episodes, in case of repeated illnesses such as urinary tract infections or disease in women. Very often, studies just report on the percentage of women they are studying who have a condition, without specifying the time period covered or the population at risk. This makes it impossible to compare across settings or studies.
|Common Maternal Mortality Indicators|
|1. Maternal mortality ratio: deaths per 100,000 live births per year|
|2. Maternal mortality rate: deaths per 100,000 women 15-49 per year|
|3. Lifetime risk: probability of death over reproductive life|
|4. Proportion of deaths: proportion of maternal (or pregnancy-related) deaths among women of reproductive age|
What are the key data sources?
The range of data sources at national and international level have changed little over time: civil and vital registration, and population-based surveys and censuses are still the main source of maternal mortality data. Data collected from these sources (if collected at all), are often captured routinely and not for any particular actionable purpose. A new initiative from low- and middle-income countries, referred to as the Maternal Death Surveillance and Response, is a tool which assists in collecting more comprehensive data on maternal mortality, with an eye to action.
What is needed to further improve maternal health surveillance?
There has been an emphasis on strengthening vital registration and cause-of-death assignment monitoring for the specific purpose of measuring and improving maternal health outcomes3. Improving the frequency, completeness and reliability of data are key to improving maternal health surveillance as a whole.
The UK Confidential Enquiry into Maternal Deaths is arguably the most comprehensive existing surveillance system for maternal death, with an inclusive examination of clinical circumstances and context reported by midwives, obstetricians, coroners, members of the public, the media, vital statistics records and linked birth-death records3. The lesson learnt from this surveillance method is that maternal death audits and severe maternal morbidity surveillance are complementary activities, which are able to inform policies and activities to reduce preventable maternal mortality.
Another example of an improvement of maternal health surveillance is the integration of m-Health strategies into national health information systems in some of the most remote and resource-limited settings6. As a result, frontline workers equipped with simple devices are able to efficiently gather census population denominators (e.g. women of reproductive age, pregnant women) and systematically plan surveillance and follow up. Simple measurement for action surveillance systems like this could drastically improve the monitoring of maternal health outcomes and be key to informing best practice and effective intervention strategies. Details on the social circumstances and clinical context surrounding each maternal death and morbid episode are important in lesson learning and informing future practice.
© The London School of Hygiene & Tropical Medicine