Global, regional, and national levels of maternal mortality, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015

Abstract

Background: In transitioning from the Millennium Development Goal to the Sustainable Development Goal era, it is imperative to comprehensively assess progress toward reducing maternal mortality to identify areas of success, remaining challenges, and frame policy discussions. We aimed to quantify maternal mortality throughout the world by underlying cause and age from 1990 to 2015.

Methods: We estimated maternal mortality at the global, regional, and national levels from 1990 to 2015 for ages 10-54 years by systematically compiling and processing all available data sources from 186 of 195 countries and territories, 11 of which were analysed at the subnational level. We quantified eight underlying causes of maternal death and four timing categories, improving estimation methods since GBD 2013 for adult all-cause mortality, HIV-related maternal mortality, and late maternal death. Secondary analyses then allowed systematic examination of drivers of trends, including the relation between maternal mortality and coverage of specific reproductive health-care services as well as assessment of observed versus expected maternal mortality as a function of Socio-demographic Index (SDI), a summary indicator derived from measures of income per capita, educational attainment, and fertility.

Findings: Only ten countries achieved MDG 5, but 122 of 195 countries have already met SDG 3.1. Geographical disparities widened between 1990 and 2015 and, in 2015, 24 countries still had a maternal mortality ratio greater than 400. The proportion of all maternal deaths occurring in the bottom two SDI quintiles, where haemorrhage is the dominant cause of maternal death, increased from roughly 68% in 1990 to more than 80% in 2015. The middle SDI quintile improved the most from 1990 to 2015, but also has the most complicated causal profile. Maternal mortality in the highest SDI quintile is mostly due to other direct maternal disorders, indirect maternal disorders, and abortion, ectopic pregnancy, and/or miscarriage. Historical patterns suggest achievement of SDG 3.1 will require 91% coverage of one antenatal care visit, 78% of four antenatal care visits, 81% of in-facility delivery, and 87% of skilled birth attendance.

Interpretation: Several challenges to improving reproductive health lie ahead in the SDG era. Countries should establish or renew systems for collection and timely dissemination of health data; expand coverage and improve quality of family planning services, including access to contraception and safe abortion to address high adolescent fertility; invest in improving health system capacity, including coverage of routine reproductive health care and of more advanced obstetric care-including EmOC; adapt health systems and data collection systems to monitor and reverse the increase in indirect, other direct, and late maternal deaths, especially in high SDI locations; and examine their own performance with respect to their SDI level, using that information to formulate strategies to improve performance and ensure optimum reproductive health of their population.

Funding: Bill & Melinda Gates Foundation.

Copyright © 2016 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY license. Published by Elsevier Ltd.. All rights reserved.

Figures

Figure 1. Analytical flow chart for the estimation of maternal mortality for GBD 2015

Ovals represent data inputs, square boxes represent analytical steps, cylinders represent databases, and parallelograms represent intermediate and final results. Numbers are steps of the prcoess. The flowchart is colour-coded by major estimation component: data preparation and overall maternal mortality in blue; cause-specific and timing-specific estimation in green; analysis and data specific to the role of HIV/AIDS in maternal mortality in pink; steps related to demographic and computational processes that ensure internal consistency in orange, and final estimates in dark blue. GBD=Global Burden of Disease. ICD=Internatinal Classification of Diseases. COD=causes of death. Epi=epidemiology. DHS=Demographic and Health Survey. CODEm=causes-of-death ensemble modelling. RR=relative risk. MMR=maternal mortality ratio. WPP=World Population Prospects. EPP=Estimation and Projection Package. RR=relative risk. Preg+=pregnant. Preg–=non-pregnant.

Figure 2. ICD-10 vital registration redistribution pattern from cause-specific and garbage codes to maternal-mortality specific GBD causes, global, all years combined

The list of causes on the left are raw ICD-10 cause codes according to death certification data sources and those on the right are the final target aetiologies for maternal mortality. The height of each bar is proportional to the number of deaths in each category. The colours are for ease of visualisation. Redistribution categories: A41=other sepsis; A419=sepsis, unspecified organism; D649=anaemia, unspecified; D65=disseminated intravascular coagulation; G809=cerebral palsy, unspecified; G931=anoxic brain damage, not elsewhere classified; I26=pulmonary embolism; I269=pulmonary embolism without acute cor pulmonale; I743=embolism and thrombosis of arteries of the lower extremities; I749=embolism and thrombosis of unspecified artery; K650=generalised (acute) peritonitis; K659=peritonitis, unspecified; N179=acute kidney failure, unspecified; N19=unspecified kidney failure; O95=obstetric death of unspecified cause; R98=unattended death; R99=ill-defined and unknown cause of mortality; ZZZ=causes violating age/sex limitations); reg_gc_left_hf_anaemia=anaemia due to left heart failure; other garbage=all other garbage codes. ICD-10=International Classification of Diseases 10. GBD=Global Burden of Disease.

Figure 3. Global results with 95% uncertainty interval (UI) for maternal deaths, maternal mortality ratio (MMR; number of deaths per 100 000 livebirths), and annualised rate of change (ARC) in MMR by year, 1990–2015

Figure 4. Maternal mortality ratio (MMR; number of deaths per 100 000 livebirths) for countries and territories, 2015

The map is colour-coded according to the national MMR in the year 2015. Lowest MMR is shown in purple and highest in dark red. Inset images help to show smaller countries. ATG=Antigua. VCT=Saint Vincent and the Grenadines. Isl=Islands. FSM=Federated States of Micronesia. LCA=Saint Lucia. TTO=Trinidad and Tobago. TLS=Timor-Leste.

Figure 5. Co-evolution of maternal mortality ratio (MMR; number of livebirths per 100 000 livebirths) with SDI globally and for GBD regions, 1990–2015

Coloured lines show global and region values for MMR. Each point in a line represents one year starting at 1990 and ending at 2015. In all regions, SDI has increased over time so progress in SDI is associated with points further to the right and later years for a given region. The black lines indicate expected trajectories for each geography expected on the basis of SDI alone. SDI=Socio-demographic Index.

Figure 6. Difference between observed annualised rate of change (ARC) in maternal mortality ratio (MMR; number of deaths per 100 000 livebirths) and expected ARC on the basis of Socio-demographic Index (SDI) alone from 2000 to 2015 for countries and territories

The map displays the difference between the observed average annual rate of change in MMR and the average annual rate of change that would have been expected based on the change in each country and territory’s SDI from 2000 to 2015. Values below zero indicate faster than expected progress while those above zero indicate MMR has improved more slowly than expected. ATG=Antigua. VCT=Saint Vincent and the Grenadines. Isl=Islands. FSM=Federated States of Micronesia. LCA=Saint Lucia. TTO=Trinidad and Tobago. TLS=Timor-Leste.

Figure 7. Global proportion of total maternal deaths by underlying cause and age, 2015

The stacked area graph shows the proportion of total maternal deaths due to each cause globally in 2015 as a function of female age group.

Figure 8. Expected relationship between cause-specific maternal mortality ratio (MMR; number of livebirths per 100 000 livebirths) and SDI (left) and proportion of maternal deaths due to each underlying cause and SDI (right)

These stacked curves represent the average relation between SDI and each cause of maternal mortality observed across all geographies over the time period 1990–2015. In each figure, the y axis goes from lowest SDI up to highest SDI. To the left of the midline are maternal mortality ratios (MMR; number of deaths per 100 000 livebirths), and the right-hand side shows the proportion of the total in order to highlight the different cause pattern in high SDI locations. SDI=Socio-demographic index.

Figure 9. Comparison of annualised rate of change (ARC) in maternal mortality ratio (MMR; number of deaths per 100 000 livebirths) from GBD 2015 and MMEIG 2015 for all countries included in both analyses, 1990–2015

This scatterplot shows the net difference in average annualised rate of change (ARC) in maternal mortality ratio (MMR; number of deaths per 100 000 livebirths) estimates between GBD 2015 and MMEIG 2015 over the entire time period from 1990 to 2015. MMEIG 2015 average ARC results are shown on the y-axis and GBD 2015 average ARC are shown on the x-axis. Points are colour-coded according to GBD super region. All countries under the horizontal dotted line were estimated by MMEIG to have achieved Millennium Development Goal (MDG) 5. Those to the left of the dotted line were estimated to have achieved MDG 5 by GBD 2015. UN Maternal Mortality Estimation Inter-agency Group. AFG=Afghanistan. BHS=The Bahamas. BLR=Belarus. BTN=Bhutan. BWA=Botswana. CAN=Canada. CHN=China. CMR=Cameroon. COD=Democratic Republic of the Congo. COG=Congo (Brazzaville). CPV=Cape Verde. DJI=Djibouti. EST=Estonia. FJI=Fiji. GUY=Guyana. IRN=Iran. ISL=Iceland. JAM=Jamaica. JOR=Jordan. KAZ=Kazakhstan. KHM=Cambodia. LAO=Laos. LBN=Lebanon. LBY=Libya. LSO=Lesotho. LUX=Luxembourg. MAR=Morocco. MDV=Maldives. MNG=Mongolia. POL=Poland. PRK=North Korea. ROU=Romania. RWA=Rwanda. SAU=Saudi Arabia. SLE=Sierra Leone. SRB=Serbia. SSD=South Sudan. SUR=Suriname. SWZ=Swaziland. TCD=Chad. TUR=Turkey. TLS=Timor-Leste. TON=Tonga. ZAF=South Africa. ZWE=Zimbabwe.