Neonatal mortality levels for 193 countries in 2009 with trends since 1990: a systematic analysis of progress, projections, and priorities

Abstract

Background: Historically, the main focus of studies of childhood mortality has been the infant and under-five mortality rates. Neonatal mortality (deaths <28 days of age) has received limited attention, although such deaths account for about 41% of all child deaths. To better assess progress, we developed annual estimates for neonatal mortality rates (NMRs) and neonatal deaths for 193 countries for the period 1990-2009 with forecasts into the future.

Methods and findings: We compiled a database of mortality in neonates and children (<5 years) comprising 3,551 country-years of information. Reliable civil registration data from 1990 to 2009 were available for 38 countries. A statistical model was developed to estimate NMRs for the remaining 155 countries, 17 of which had no national data. Country consultation was undertaken to identify data inputs and review estimates. In 2009, an estimated 3.3 million babies died in the first month of life-compared with 4.6 million neonatal deaths in 1990-and more than half of all neonatal deaths occurred in five countries of the world (44% of global livebirths): India 27.8% (19.6% of global livebirths), Nigeria 7.2% (4.5%), Pakistan 6.9% (4.0%), China 6.4% (13.4%), and Democratic Republic of the Congo 4.6% (2.1%). Between 1990 and 2009, the global NMR declined by 28% from 33.2 deaths per 1,000 livebirths to 23.9. The proportion of child deaths that are in the neonatal period increased in all regions of the world, and globally is now 41%. While NMRs were halved in some regions of the world, Africa's NMR only dropped 17.6% (43.6 to 35.9).

Conclusions: Neonatal mortality has declined in all world regions. Progress has been slowest in the regions with high NMRs. Global health programs need to address neonatal deaths more effectively if Millennium Development Goal 4 (two-thirds reduction in child mortality) is to be achieved.

Figure 1. Data sources used for NMR estimation.

Year of most recent survey with neonatal and under-five mortality rates information is indicated as greater or less than 5 y before 2008. Countries with no relevant, recent data of any kind are indicated as not available.

Figure 2. Geographical regions used in study.

The map illustrates the geographical regions used both in the statistical model and when summarizing results at regional level in the main text (Table S3 summarizes estimated neonatal mortality trends by MDG regions).

Figure 3. Methods used to estimate NMRs.

The map illustrates the NMR estimation method used for each of the 193 countries estimated for.

Figure 4. Modeled relationship between U5MR and NMR.

The blue curve illustrates our fitted statistical model predicting NMR for method 2 countries (see Methods). The curve was drawn with country and regional random effects assumed zero to show the assumed functional relationship between U5MR and NMR—in practice, within our multilevel statistical model, these random effects vary by country and region, respectively, such that the precise functional relationship between NMR and U5MR differs between countries. The green curve is similar to the blue model without allowing for a nonlinear association on the log scale. Compared to the green curve, the blue curve allows for more plausible changes in NMR at lower levels of U5MR; particularly, the green curve implies impossible NMRs at small U5MRs for countries and regions with positive random effects, as NMR would exceed U5MR. For comparison, the red line illustrates a linear relationship on the normal scale, NMR  =  U5MR, which is highly improbable, as it would allow for the same change in NMR for a given change in U5MR at all levels of U5MR.

Figure 5. Regional trends in NMRs and numbers 1990–2009.

(A) NMRs. (B) Neonatal deaths. (C) Percentage of global deaths per region. (D) Percentage of child (under 5 y) deaths in neonatal period.

Figure 6. NMRs in 2009.

The map illustrates the NMR in year 2009 for each of the 193 countries estimated for.

Figure 7. Changes in NMRs between 1990 and 2009.

The map illustrates the change in NMR between the years 1990 and 2009 for each of the 193 countries estimated for.

Figure 8. Forecasting the number of years for low- and middle-income regions to reduce NMR to the current rate in HICs.

The graph illustrates when each region of the world attains a NMR of 3.6 as observed in HICs in 2009—the year each region attains a NMR of 3.6 is specified in parenthesis. Regional NMRs are illustrated as constant from the year they achieve a NMR of 3.6. Forecasting based on average annual changes in the NMR over the 10-y period 1999–2009.