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. 2012 Jul 13;3(2):2151-7509.1038.
doi: 10.1515/2151-7509.1038.

A New Method for Deriving Global Estimates of Maternal Mortality

John R Wilmoth  1 , Nobuko Mizoguchi  2 , Mikkel Z Oestergaard  3 , Lale Say  3 , Colin D Mathers  3 , Sarah Zureick-Brown  4 , Mie Inoue  3 , Doris Chou  3
Affiliations

A New Method for Deriving Global Estimates of Maternal Mortality

John R Wilmoth et al. Stat Politics Policy. .

Abstract

Maternal mortality is widely regarded as a key indicator of population health and of social and economic development. Its levels and trends are monitored closely by the United Nations and others, inspired in part by the UN's Millennium Development Goals (MDGs), which call for a three-fourths reduction in the maternal mortality ratio between 1990 and 2015. Unfortunately, the empirical basis for such monitoring remains quite weak, requiring the use of statistical models to obtain estimates for most countries. In this paper we describe a new method for estimating global levels and trends in maternal mortality. For countries lacking adequate data for direct calculation of estimates, we employed a parametric model that separates maternal deaths related to HIV/AIDS from all others. For maternal deaths unrelated to HIV/AIDS, the model consists of a hierarchical linear regression with three predictors and variable intercepts for both countries and regions. The uncertainty of estimates was assessed by simulating the estimation process, accounting for variability both in the data and in other model inputs. The method was used to obtain the most recent set of UN estimates, published in September 2010. Here, we provide a concise description and explanation of the approach, including a new analysis of the components of variability reflected in the uncertainty intervals. Final estimates provide evidence of a more rapid decline in the global maternal mortality ratio than suggested by previous work, including another study published in April 2010. We compare findings from the two recent studies and discuss topics for further research to help resolve differences.

Keywords: AIDS mortality; Millennium Development Goals; maternal mortality; multilevel regression model.

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Figures

Figure 1
Figure 1
Deviance scores as a function of parameter k for two variants of the multilevel regression model
Figure 2
Figure 2
Total numbers of maternal deaths in Sub-Saharan Africa implied by different values of parameter u
Figure 3
Figure 3
Six country examples of the estimated maternal mortality ratio, with 95% uncertainty intervals and national estimates, 1990–2008 (Note: National estimates, from a separate database maintained by UNICEF, are shown here with reference time intervals. Model inputs, from original sources but with various adjustments, refer to similar intervals, but each is plotted here as a dot at the interval midpoint. In addition to differences of level as discussed in the text, the two collections disagree slightly in certain cases regarding the exact time reference for a given estimate.)
Figure 4
Figure 4
Two country examples of the estimated maternal mortality ratio with and without AIDS-related maternal deaths, 1990–2008
Figure 5
Figure 5
Estimated maternal mortality ratio with and without AIDS-related maternal deaths, and IHME estimates with and without HIV, 1990–2008
See this image and copyright information in PMC

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