Review
Global and regional estimates of preeclampsia and eclampsia: a systematic review

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Abstract

Reduction of maternal mortality is a target within the Millennium Development Goals. Data on the incidence of preeclampsia and eclampsia, one of the main causes of maternal deaths, are required at both national and regional levels to inform policies. We conducted a systematic review of the incidence of hypertensive disorders of pregnancy (HDP) with the objective of evaluating its magnitude globally and in different regions and settings. We selected studies using pre-specified criteria, recorded database characteristics and assessed methodological quality of the eligible studies reporting incidence of any HDP during the period 2002–2010. A logistic model was then developed to estimate the global and regional incidence of HDP using pre-specified predictor variables where empiric data were not available. We found 129 studies meeting the inclusion criteria, from which 74 reports with 78 datasets reporting HDP were analysed. This represents nearly 39 million women from 40 countries. When the model was applied, the overall estimates are 4.6% (95% uncertainty range 2.7–8.2), and 1.4% (95% uncertainty range 1.0–2.0) of all deliveries for preeclampsia and eclampsia respectively, with a wide variation across regions. The figures we obtained give a general idea of the magnitude of the problem and suggest that some regional variations might exist. The absence of data in many countries is of concern, however, and efforts should be made to implement data collection and reporting for substantial statistics. The implementation of large scale surveys conducted during a short period of time could provide more reliable and up-to-date estimations to inform policy.

Introduction

Hypertensive disorders of pregnancy (HDP) are important causes of maternal mortality. They account for nearly 18% of all maternal deaths worldwide, with an estimated 62,000 to 77,000 deaths per year [1]. As there are about 127 million births annually in the world [2], the risk of maternal death from HDP is approximately one in 1700 to one in 2100 deliveries globally. There is, however, a wide variation across regions in the lifetime risk of a woman dying from maternal causes (from 1 in 3800 in developed countries to 1 in 39 in Sub-Saharan Africa) [3], as well as in the contribution of HDP to the total maternal mortality. In Latin America and the Caribbean HDP represent the highest cause of death, being the second cause in developed countries [1].

There are broad categories for the classification of HDP. These are gestational hypertension, or pregnancy-induced hypertension, which is hypertension without proteinuria; preeclampsia, which is hypertension with proteinuria; and chronic hypertension, or essential hypertension, which is pre-existing hypertension with or without superimposed preeclampsia [4]. Most of the morbidity is concentrated among pregnancies complicated by preeclampsia or eclampsia (when convulsions occur in a woman with preeclampsia), and for every woman who dies, approximately 20 others suffer severe morbidity [5].

Regional, country and provincial variations on the abovementioned global figures are likely to exist but are not currently known. There is therefore a need to establish the magnitude and the regional distribution of HDP around the world to adequately inform reproductive health policies and programmes. We conducted a systematic review of the incidence of HDP with the objective of evaluating the magnitude of the problem globally and in different regions and settings.

Section snippets

Methods

We used theWorld Health Organization (WHO) Systematic Review of Maternal Mortality and Morbidity Project Protocol as a template [1], [6], considering the same criteria for screening, identification and selection of studies to all potentially eligible papers published during the period 2002–2010.

Study selection for modelling and direct estimations

Fig. 1 summarises the identification and selection of the articles and datasets for incorporation into the analysis. For the period 2002–2010, of the 11,637 citations screened, there were 129 studies from 44 countries meeting the inclusion criteria. The final number of reports analysed for this period was 74, with 78 datasets having HDP as an endpoint for 40 countries (Fig. 2). Overall, 78 datasets were included in the final analysis: 52 of these reported preeclampsia, 42 reported eclampsia, 20

Summary of main findings, strengths and limitations

This study is the first systematic analysis providing estimates of the global distribution of incidence of preeclampsia and eclampsia. From our datasets, the model-based incidence of preeclampsia and eclampsia are approximately 4.6% and 1.4% of all deliveries, with a wide variation across the different regions of the world. Although this could represent different risks of developing preeclampsia in some regions or different management of preeclampsia cases to prevent eclampsia in others, the

Contributors

LS, EA and DC conceived the review. All authors developed the methodology. ALG performed the literature search and prepared the vital registration data. ALG and EA considered studies for inclusion and extracted the data. CC performed the statistical analysis. EA, CC, LS and DC drafted the text and tables. All authors reviewed and approved the manuscript.

Conflict of interest statement

The authors declare that they have no conflicts of interest. Two WHO staff members are part of the team who conducted the study. The findings in this paper represent the conclusions of the authors.

Funding

The Department of Reproductive Health and Research, WHO through the Special Programme of Research, Development, and Research Training in Human Reproduction and the US Fund for UNICEF through a grant from the Bill and Melinda Gates Foundation to CHERG.

Acknowledgements

Special thanks to Ann Beth Moller for her contribution with translations of original papers published in other languages, to Daniel Giordano, Hugo Gamerro and Fernando Burgueño from Centro Rosarino de Estudios Perinatales (CREP) for the design of the database and data entry.

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