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Maternal mortality for 181 countries, 1980-2008: a systematic analysis of progress towards Millennium Development Goal 5
Global Health Sciences Literature Digest
Published October 18, 2010
Journal Article

Hogan MC, Foreman KJ, Naghavi M, Ahn SY, Wang M, Makela SM, et al. Maternal mortality for 181 countries, 1980-2008: a systematic analysis of progress towards Millennium Development Goal 5. Lancet. 2010;375:1609-1623.

In Context

The target for Millennium Development Goal 5 is to reduce the maternal mortality ration (MMR) by three quarters from 1990-2015. The most recent assessment of maternal mortality estimated 535,900 maternal deaths in 2005.(1) Several recent studies and the development of new methodologies for estimating maternal mortality provide an opportunity for reassessing maternal mortality.(2, 3, 4)

Objective

To assess levels and trends in maternal mortality from 1980 through 2008 for 181 countries.

Search Strategy

A database was constructed based primarily on WHO mortality database which was supplemented by an internet search of national statistical offices. All deaths with ICD codes 000-099 were included. Sibling history data from the demographic health surveys (DHS) and the Centers for Disease Control and Prevention (CDC) International Reproductive Health Surveys were also examined. Surveys were pooled together within countries and Gakidou-King weights were applied to correct for survivor bias. The weights were used to estimate the age-specific proportion of maternal deaths in women of reproductive age for 5-year periods starting from the time of the most recent survey in each country, for a maximum of 15 years before the most distant survey in each country.

For literature on maternal mortality estimates the authors searched PubMed using the terms "maternal mortality," "verbal autopsy," and the country names, for all countries not part of the Organisation for Economic Co-operation and Development (OECD). These countries were excluded the search because most of them have high-quality vital registration data. Maternal Mortality: a Global Factbook, published by WHO was included in the search. The Chinese scientific literature database Wanfang Data was searched using the term "maternal mortality surveillance." After review, hospital-based or intervention studies, those that used the sisterhood methods, or that were considered to be low quality were excluded.

Studies

A total of 9659 titles were identified. From these, 593 abstracts were determined to be potentially relevant and of these, 209 papers were identified. This yielded 61 studies from which data were extracted and added to the database. The term "verbal autopsy" identified 1042 titles, which resulted in 22 studies added to the database. The Wanfang Data search resulted in an additional eight papers.

Using these sources, the authors extracted the proportion of deaths attributable to maternal causes for five-year age groups ranging from 15-49 years. These proportions were applied to the new time series of adult female mortality based on mortality for each country in 1970-2010. The MMRs were calculated using population and live births obtained from the UN Population Division.

Outcome Measures

Maternal mortality. Early maternal mortality included deaths during pregnancy or less than 42 days after termination of the pregnancy and deaths from 42 days to one year were classified as late maternal deaths. Causes of deaths were categorized as: direct obstetric causes, causes aggravated by pregnancy (referred to as 'indirect' causes), HIV infection, and incidental causes unrelated to pregnancy. The MMR was calculated using early deaths due to these causes other than those unrelated to pregnancy. This is consistent with methods recommended in the ICD and MDG manuals. The authors applied a series of statistical methods to obtain MMR estimates; for the details of these analyses the article and its associated web appendix should be reviewed.

Results

There were an estimated 342,900 (uncertainty interval 302,100-394,300) maternal deaths worldwide in 2008 compared with 526,300 (446,400-629,600) deaths estimated in 1980. This corresponds to rate of decline of 1.5%. The global MMR decreased from 422 (358-505) in 1980 to 320 (272-388) in 1990, to 251 (221-289) per 100,000 live births in 2008. The yearly rate of decline of the global MMR since 1990 was 1.3% (1.0-1.5). There was substantial variation in the yearly decline in the MMR across countries between 1990 and 2008, with a decline of 8-8% (8.7-14.1) in the Maldives to an increase of 5.5% (5.2-5.6) in Zimbabwe. India, Nigeria, Pakistan, Afghanistan, Ethiopia, and the Democratic Republic of the Congo accounted for over 50% of all maternal deaths. HIV accounts for a large proportion of maternal deaths; in the absence of HIV, there would have been 281,500 (243,900-327,900) maternal deaths worldwide in 2008.

Conclusions

While not evenly distributed, there has been a decline in maternal mortality in the 181 countries examined.

Quality Rating

This was a very well-conducted study. The authors provide detailed information regarding the methods used to search for data and the statistical methods applied to derive the estimates of maternal deaths and the MMR. However, given the variation in the quality of vital registration systems, there is likely to be both over- and under-estimates of these outcomes in the countries included in the analysis.

Programmatic Implications

The decline in maternal deaths and MMR is likely due to the global decrease in the total fertility rate, and increases in the income per person, maternal educational achievement, and births attended to by skilled personnel. However, HIV has a substantial and adverse effect on maternal mortality.(5, 6) Expanded efforts to diagnose and treat HIV throughout the world should result in continued declines in maternal deaths and the MMR. To achieve the MDG target, a decline in maternal deaths of 5.5% is needed. Given the findings from this study, effective methods to continue the decrease in maternal deaths as well as methods to prevent and treat HIV are needed.

References

  1. Hill K, Thomas K, AbouZahr C, et al, on behalf of the Maternal Mortality Working Group. Estimates of maternal mortality worldwide between 1990 and 2005: an assessment of available data. Lancet. 2007; 370: 1311-19.
  2. Naghavi M, Makela S, Foreman K, O'Brien J, Lozano R. Algorithms for enhancing public health utility of national causes of death data. Popul Health Metr (in press).
  3. Gakidou E, King G. Death by survey: estimating adult mortality without selection bias from sibling survival data. Demography. 2006;43: 569-85.
  4. Rajaratnam JK, Marcus JR, Levin-Rector A, et al. Worldwide mortality in men and women aged 15-59 years from 1970 to 2010: a systematic analysis. Lancet. 2010 May 15;375(9727):1704-20.
  5. Bicego G, Boerma J, Ronsmans C. The effect of AIDS on maternal mortality in Malawi and Zimbabwe. AIDS. 2002; 16: 1078-81.
  6. McIntyre J. Mothers infected with HIV: reducing maternal death and disability during pregnancy. Br Med Bull. 2003; 67: 127-35