Maternal Mortality

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Maternal Mortality

• Liliana Carvajal
• Vibeke Oestreich Nielsen
• Armando H. Seuc
• UNICEF
• Statistics Norway
• WHO

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Background
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MDG 5 Improve Maternal Health

• Target 5.A Reduce by three quarters, between
  1990 and 2015, the maternal mortality ratio
• 5.1 Maternal mortality ratio (MMR)
• 5.2 Proportion of births attended by skilled
  health personnel (SAB)
• Target 5.B Achieve, by 2015, universal access to
  reproductive health
• 5.3 Contraceptive prevalence rate
• 5.4 Adolescent birth rate
• 5.5 Antenatal care coverage
• at least one visit and at least four visits
• 5.6 Unmet need for family planning

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Maternal Mortality

• Target 5.A Reduce by three quarters, between
  1990 and 2015, the maternal mortality ratio
• 5.1 Maternal mortality ratio
• 5.2 Proportion of births attended by skilled
  health personnel
• Initially updates every 5 year since 1990 by WHO,
  UNICEF, UNFPA The World Bank joined in 2005
• 2008 update An academic team at University of
  Berkeley in collaboration with MMEIG
• 2010 update idem

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Measuring Maternal Mortality
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Trends in Maternal Mortality 1990 to 2008

• Reviewed by the technical advisory group (TAG)
  with experts from academic institutions
  Berkeley, Harvard, Hopkins, Texas, Aberdeen,
  Umea, Statistics Norway
• Countries consulted for comments on methodology
  and additional input

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Trends in Maternal Mortality 1990 to 2010

• Reviewed by the technical advisory group (TAG)
  with experts from academic institutions
  Berkeley, Harvard, Hopkins, Texas, Aberdeen,
  Umea, Statistics Norway
• Countries consulted for comments on methodology
  and additional input

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General framework of the maternal mortality
estimates 1990-2008 and 1990-2010

• Levels and trends of maternal mortality between
  1990 and 2008 for 172 countries (1990-2010 for
  181 countries)
• Hierarchical/multilevel linear regression model
• The model input data is the PMDF (proportion
  maternal among all female deaths 15-49) adjusted
  for completeness and definition
• Covariates the log(GDP), log(GFR) and SAB
• The final output takes into account the maternal
  mortality related with the HIV/AIDS

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Definitions used

• Maternal death 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
  but not from accidental or incidental causes.
  ICD-10, WHO,1994
• Pregnancy-related death the death of a woman
  while pregnant or within 42 days of termination
  of pregnancy

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Estimated measures

• Maternal Mortality Ratio (MMR) Ratio of maternal
  deaths in a period to live births (proxy for
  risky events) in the same period (x 100,000).
• Number of maternal deaths
• PMDF Proportion of maternal among female deaths
  15-49
• Lifetime risk of a maternal death An estimate of
  the likelihood that a woman who survives to age
  15 will die of maternal causes
• proportion of women reaching reproductive age who
  would die of maternal causes, taking into account
  competing causes

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Input data to the model PMDF

• PMDF is considered less subject to
  under-reporting than MMR (maternal and
  non-maternal deaths likely to be under-reported
  to similar degree)
• Maternal deaths as defined by ICD is difficult to
  capture usually all deaths in pregnancy
  measured
• Efforts have been made to adjust for
• under reporting
• definition
• For the model the HIV/AIDS component was taken
  out from the PMDF the HIV/AIDS component is then
  added back after the model fitting

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Input database

• 1990-2008 Database of 172 countries -
  territories, from 1985 onwards
• 1990-2010 Database of 181 countries -
  territories, from 1985 onwards
• Nationally representative data
• gt focusing on sources where PMDF is possible to
  compute

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Methods of Data Collection, Estimation
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Sources of Data

• Civil registration systems with cause of death
  assigned by attending physician
• Household surveys with sibling histories
• Sample vital registration systems
• Reproductive Age Mortality Surveys (RAMOS) not
  very common
• Population censuses with questions on household
  deaths
• Hospital- or facility-based studies
• Other

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Data on maternal mortality availability
Sources Number of surveys Number of country-years
Civil Registration 1891 1891 (2125)
Surveys with Sibling Histories 105 819 (895)
Population Censuses 18 19 (19)
Other (eg special surveys, verbal autopsies, surveillance) 80 113 (161)
Total 2094 2842 (3200)
1990-2010 estimations
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Data available in the Region
Group
Afghanistan B
Bangladesh B
Bhutan B
Cambodia B
China B
Indonesia B
Iran B
Lao B
Mongolia C
Myanmar B
Nepal B
Pakistan B
Philippines B
Thailand B
Papua New Guinea C

1. Civil registration characterized as complete,
   with good attribution of cause of death
2. Countries lacking good complete registration data
   but where other types of data are available
3. No national data on maternal mortality

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General Problems with Maternal Mortality
Measurement

• Rare events
• National trends unstable
• For household surveys requires very large samples
• Certain types of maternal deaths hard to identify
  (especially abortion-related)
• Non-VR methods tend to measure pregnancy-related
  mortality PRMR

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Civil Registration Data

• WHO estimates that approx. 72 (out of 193) member
  states have complete recording of deaths
• But not all have adequate cause of death data
• Even in countries with complete VR,
  classification of deaths as maternal is
  problematic
• Recent increase in MMR (47 2002 to 2004) in US
  due to change of death certificate
• Issues
• 14 studies (confidential enquiries, record
  linkages) of countries with complete
  registration a median underestimation of 0.5
  true maternal deaths were incorrectly recorded as
  non-maternal

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Household Surveys With Sibling Histories

• Key questions for sibling history
• Each sibling listed individually
• Record sex
• Record age in completed years for surviving sibs
• Record year of death, age at death for dead sibs
• For deaths of women of reproductive age, 3
  questions about timing of death relative to
  pregnancy
• Widely used by DHS program (41countries,65
  surveys)
• Issues
• Measures pregnancy-related mortality
• Estimates are usually made for 7 years before
  survey
• May under-estimate overall mortality

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Sample Vital Registration Systems

• Special procedures in random sample of areas
  (4,000 in India, 160 in China)
• Continuous monitoring of vital events plus
  6-monthly household survey (India)
• Cause of death identified by verbal autopsy (VA)
  (India) or case records plus VA (China)
• Issues
• Requires considerable administrative
  sophistication
• Cannot be implemented rapidly
• Needs periodic evaluation

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RAMOS Studies

• Starting point is complete listing of deaths of
  women of reproductive age
• Best starting point is close to complete VR
• Key feature is triangulation among data sources
  (eg church records, burial grounds) to identify
  missed deaths
• May be done for a sample (but has to be large)
• Each death is investigated in detail to determine
  whether or not it was maternal
• Hospital, health facility records
• Household interviews
• Issues
• Results may be no better than the frame of deaths
• MMR also needs number of births

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Censuses with Questions on Deaths

• Population censuses can include questions on
  deaths in households in defined recent reference
  period
• Reported deaths of reproductive aged women
  trigger questions about the timing of death
  relative to pregnancy
• Issues
• Pregnancy-related mortality
• Census misses deaths in single-person households
• Death of head of household may result in
  household breakup
• Experience suggests there is almost always some
  under-reporting
• Need to evaluate carefully
• No consensus as to the quality of the data
  obtained

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Facility-Based Studies

• Useful for identifying areas for improved care
  (confidential enquiries)
• Potential for gold standard case identification
  (case notes)
• Facility deaths (and births) are selected on
  characteristics that may not be known
• Not readily generalizable to a national MMR
  estimate

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Estimation (Modelling)
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Modelling

• Countries in Group A
• No modelling was used
• Essentially data from CR were adjusted by a 1.5
  factor

• Countries in Groups B and C
• Multilevel model was used to predict PMDF with
  GDP, GFR and SAB as predictors
• Group C countries borrowed from other countries
  in the region
• PMDF was converted into MMR

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Input data to the modelAdjustment by type of
source

• Adjustment for completeness of reporting
  specified in relation to the type of data
• CR system Review of recent literature on
  underestimation of maternal deaths in CR systems
• adjustment by a factor of 1.5
• Sibling histories age-standardization,
• 1.1 adjustment (underestimation of early
  pregnancy deaths)
• 0.9, 0.85 adjustment (remove accidental deaths)
• Other special studies (e.g., RAMOS)
• 1.1 adjustment

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Covariates

• GDP gross domestic product PPP per capita, in
  constant 2005 international dollar the World
  Bank series, complemented by other sources
• GFR general fertility rate, the number of births
  in a population divided by the number of women at
  reproductive ages UNPD World Population
  Prospects
• SAB the proportion of deliveries with a skilled
  attendant at birth from UNICEF database

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Covariates and the model

• A time series of these three covariates were
  constructed for the 1985-2008 (1985-2010) period
• Time-matched average values of the covariates for
  time intervals corresponding to the period of
  each observation of the dependent variable PMDF
  were computed
• A hierarchical/multilevel model with three main
  covariates, plus random effects for countries and
  regions and an offset which will adjust the
  denominator of PMDF for AIDS.

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Input data to the modelDefinition and HIV/AIDS
adjustment
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Excluding AIDS-related deaths from PMDF

• PMDFadj1(PMDFadj0 u v a) (1-p)d
• removes from numerator
• a fraction of AIDS deaths among deaths to women
  aged 15-49
• v proportion of such AIDS deaths that occur
  during pregnancy (or within 42 days after
  delivery)
• u fraction actually" counted as maternal
• log(PMDFadj1) b0 ?j ?k
• b1 log(GDP) b2 log(GFR)
• b3 SAB log(1-a) e
• removes from denominator
• AMDF AIDS-adjusted (denominator) PMDF
  (PMDFadj1)/(1-a)

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Final estimates of PMDF

• PMDFa splitting the UNAIDS estimate of total
  AIDS deaths among women aged 15-49
• PMDFa u v a
• a fraction of AIDS deaths among deaths to
  women aged 15-49
• v proportion of such AIDS deaths that occur
  during pregnancy (or within 42 days after
  delivery)
• u fraction that should be" counted as
  maternal
• PMDF PMDFna PMDFa

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Uncertainty

• Components of uncertainty include
• Any remaining bias in adjusted PMDF values
• Uncertainty in model parameters (c, k, u, and pi)
• Regression prediction uncertainty within the PMDF
  model
• Possible error in MMR conversion (estimated
  births and deaths)
• Alternative models, covariates, etc.

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What is new in 2008 and 2010 compared with 2005

• Trend estimates for countries
• gt bigger database
• Definition issue addressed
• Maternal deaths related with HIV/AIDS taken into
  account
• Statistical model more detailed

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What is new in 2010 compared with 2008

• Data availability
• 3200 country-years of data in 2010 compared with
  2842 in 2008 (13 increase)
• Total female deaths in the reproductive age were
  updated backward (routine updating process by
  WHO)
• Countries included
• 181 in 2010 vs. 172 in 2008. The population
  cut-off for country inclusion was 100000 in 2010
  vs. 250000 in 2008

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Country consultation
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Country consultation

• CL.33.2011 (8 December 2011)
• Following WHOs quality standards for data
  publication and prior to the official release of
  the above estimates, WHO is consulting with its
  Member States to review each individual country
  estimate in order to identify and make use of
  primary data sources that may not have been
  previously identified.
• Focal point identification and review. Comments
  received during consultation.
• Accepted amendments to data input
• source of reference clearly identified