UNIVERSITY OF WASHINGTON

Maternal mortality for 181 countries, 1980-2008

A systematic analysis of progress towards Millennium Development Goal 5

Opportunities for a Robust Reassessment of Maternal Mortality

• Global Burden of Disease (GBD) study has undertaken a comprehensive analysis of misclassification of maternal death in vital registration data

• Methodological advances in correcting sibling history data for known biases (survivor bias, recall bias) – Obermeyer et al 2010, PLoS Medicine

• Growing body of population-based verbal autopsy studies

• New estimates of all-cause reproductive-aged female mortality -- Rajaratnam et al, 2010, The Lancet

• Methodological developments in other fields provide improved statistical tools to detect spatial-temporal patterns

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Clarifying the Definition of the MMR

• Maternal death: “death of a woman while pregnant or within 42 days of termination of pregnancy…from any cause related to the pregnancy or its management, but not from accidental or incidental causes” (ICD-10)

• For inter-temporal and international comparisons, ICD and MDG manual recommend A+B+C excluding D+E+F

• Maternal mortality ratio: number of maternal deaths per 100,000 live births

  Direct Indirect HIV Incidental

Early maternal (<42 days)   A B C D

Late maternal (> 42 days & < 1 year) E F    

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Systematic Identification of Data

Vital registration data

o Naghavi et al (Population Health Metrics 2010) have undertaken a detailed study of the misclassification of maternal deaths in ICD coded vital registration data; correcting for misclassification increased maternal deaths in vital registration data on average by 42%.

Sibling history data from surveys

o Apply the Gakidou-King correction for survival bias

Deaths in the household from censuses and surveys

National and sub-national verbal autopsy

o Literature review to identify published estimates from national and sub-national population-based studies of maternal mortality

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Final Database by Source

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• No data for 21 countries, representing 2.2% of births• Each sibling history data point covers a 5-year period

Sibling History Data Needs to be Corrected for Survivor Bias

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Obermeyer et al 2010, PLoS Medicine

Analytical Approach

1. Extract proportion of all female deaths due to maternal causes from all data sources

2. Apply proportion to new adult female adult mortality time series (Rajaratnam et al, The Lancet, 2010) to arrive at maternal mortality rates by age.

3. Two stage analysis, modeling the age-specific maternal mortality rate

• Stage 1: Linear model

• Stage 2: Spatial temporal model

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Model Validation: An Essential Test

• More sophisticated models can improve measurement but it is essential that the validity of any modeling strategy be rigorously evaluated.

• Validity of alternative models tested using four types of predictive validity:

o Hold out 20% of country-years

o Hold out 20% of countries

o Hold out the first 20% of years of data for all countries

o Hold out the last 20% of years of data for all countries

• Two stage modeling strategy reduces median error by 50-60%

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Sources of Uncertainty

1. Multiple measurements for the same year often differ substantially.

2. Measurements only available for selected years

3. Models used to integrate data from multiple sources have uncertainty associated with them.

4. Methods for uncertainty estimation for global health not yet standardized. Our estimates of uncertainty for technical reasons are likely to be too large.

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India: Available Studies and Predicted MMR With Uncertainty

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Mali: Available Studies and Predicted MMR With Uncertainty

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Trend in Global Maternal Deaths

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MMR in 2008

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Top 21 Countries: 80% of Maternal Deaths

Order Country Deaths in 1000s (UI) % Cumulative % Births (%) Cumulative %1 India 68.3 (41.6-106.2) 19.9 19.9 19.7 19.72 Nigeria 36.7 (22.4-57.0) 10.7 30.6 4.4 24.13 Pakistan 20.1 (12.3-31.3) 5.9 36.5 3.9 28.04 Afghanistan 20.0 (7.5-43.1) 5.8 42.3 0.9 28.95 Ethiopia 18.2 (11.1-28.8) 5.3 47.6 2.3 31.26 Congo, the Democratic Republic of the 15.4 (9.0-24.7) 4.5 52.1 2.1 33.37 Bangladesh 11.6 (6.7-18.7) 3.4 55.5 2.5 35.88 Indonesia 9.6 (5.6-16.0) 2.8 58.3 3.1 38.99 Tanzania, United Republic of 8.0 (4.8-12.8) 2.3 60.6 1.3 40.210 China 7.3 (6.4-8.3) 2.1 62.7 13.3 53.511 Malawi 6.8 (4.0-10.9) 2.0 64.7 0.4 53.912 Côte d'Ivoire 6.8 (4.1-10.8) 2.0 66.7 0.5 54.413 Kenya 6.2 (3.6-10.2) 1.8 68.5 1.1 55.514 Chad 5.3 (3.3-8.2) 1.5 70.0 0.4 55.915 Mozambique 5.2 (3.1-8.4) 1.5 71.5 0.6 56.516 Uganda 5.2 (3.1-8.2) 1.5 73.0 1.1 57.617 Cameroon 5.0 (2.8-8.1) 1.4 74.4 0.5 58.118 Niger 4.7 (3.0-7.3) 1.4 75.8 0.6 58.719 Angola 4.6 (1.8-9.9) 1.3 77.1 0.6 59.320 Sudan 4.0 (2.5-6.0) 1.2 78.3 0.9 60.221 Mali 3.6 (2.3-5.5) 1.1 79.4 0.4 60.6

All other countries (160) 70.3 (43.0-112.2) 20.5 100.0 39.3 100.0Total 342.9 100.0 100.0 100.0 100.0

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Annualized Rate of Decline in MMR, 1990 to 2008

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Progress Undocumented But Not Unexpected

• Global maternal deaths down to 342,900 in 2008

• Global total fertility rate has dropped from 3.70 in 1980 to 2.56 in 2008

• Income per capita has been rising over the period, particularly in Asia and Latin America

• Maternal education has been increasing as well

o In sub-Saharan Africa, the average years of schooling for women aged 25-44 rose from 1.5 years in 1980 to 4.4 years in 2008

• The steady, slow rise in skilled birth attendance coverage may also have contributed

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Improving Maternal Mortality Measurement in the Future

• There is more data on maternal mortality than any other cause of death.

• Improved measurement can come from three strategies:

1. Reduced misclassification of maternal deaths in complete vital registration systems – check boxes on death certificates, follow-up studies for probable maternal deaths

2. Expanded coverage of incomplete vital registration systems – e.g. South Africa raised VR coverage in a short period

3. Wider and repeated collection of sibling history data in household surveys

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Progress on MDG4 and MDG5 Can be Different0

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5

ann

ualiz

ed

dec

line

in 5

q0

(%)

-4 -2 0 2 4 6annualized decline in MMR (%)

Asia Pacific, High Income

Australasia

Europe, Western

Latin America, Southern

North America, High Income

Asia, Central

Europe, Central

Europe, Eastern

Asia, East

Asia, Southeast

Oceania

Asia, South

Caribbean

Latin America, Andean

Latin America, Central

Latin America, Tropical

North Africa/Middle East

Sub-Saharan Africa, Central

Sub-Saharan Africa, East

Sub-Saharan Africa, Southern

Sub-Saharan Africa, West

Annualized Percent Decline in 5q0 and MMR; 1990-2008

Equivalence Line

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Global Progress Toward Reducing Maternal and Child Mortality