Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2013 Aug 3;382(9890):417-425.
doi: 10.1016/S0140-6736(13)60993-9. Epub 2013 Jun 6.

Mortality risk in preterm and small-for-gestational-age infants in low-income and middle-income countries: a pooled country analysis

Joanne Katz  1 , Anne Cc Lee  2 , Naoko Kozuki  3 , Joy E Lawn  4 , Simon Cousens  5 , Hannah Blencowe  5 , Majid Ezzati  6 , Zulfiqar A Bhutta  7 , Tanya Marchant  8 , Barbara A Willey  9 , Linda Adair  10 , Fernando Barros  11 , Abdullah H Baqui  3 , Parul Christian  3 , Wafaie Fawzi  12 , Rogelio Gonzalez  13 , Jean Humphrey  14 , Lieven Huybregts  15 , Patrick Kolsteren  15 , Aroonsri Mongkolchati  16 , Luke C Mullany  3 , Richard Ndyomugyenyi  17 , Jyh Kae Nien  18 , David Osrin  19 , Dominique Roberfroid  20 , Ayesha Sania  21 , Christentze Schmiegelow  22 , Mariangela F Silveira  23 , James Tielsch  24 , Anjana Vaidya  19 , Sithembiso C Velaphi  25 , Cesar G Victora  23 , Deborah Watson-Jones  26 , Robert E Black  3 ; CHERG Small-for-Gestational-Age-Preterm Birth Working Group
Affiliations

Mortality risk in preterm and small-for-gestational-age infants in low-income and middle-income countries: a pooled country analysis

Joanne Katz et al. Lancet. .

Abstract

Background: Babies with low birthweight (<2500 g) are at increased risk of early mortality. However, low birthweight includes babies born preterm and with fetal growth restriction, and not all these infants have a birthweight less than 2500 g. We estimated the neonatal and infant mortality associated with these two characteristics in low-income and middle-income countries.

Methods: For this pooled analysis, we searched all available studies and identified 20 cohorts (providing data for 2,015,019 livebirths) from Asia, Africa, and Latin America that recorded data for birthweight, gestational age, and vital statistics through 28 days of life. Study dates ranged from 1982 through to 2010. We calculated relative risks (RR) and risk differences (RD) for mortality associated with preterm birth (<32 weeks, 32 weeks to <34 weeks, 34 weeks to <37 weeks), small-for-gestational-age (SGA; babies with birthweight in the lowest third percentile and between the third and tenth percentile of a US reference population), and preterm and SGA combinations.

Findings: Pooled overall RRs for preterm were 6·82 (95% CI 3·56-13·07) for neonatal mortality and 2·50 (1·48-4·22) for post-neonatal mortality. Pooled RRs for babies who were SGA (with birthweight in the lowest tenth percentile of the reference population) were 1·83 (95% CI 1·34-2·50) for neonatal mortality and 1·90 (1·32-2·73) for post-neonatal mortality. The neonatal mortality risk of babies who were both preterm and SGA was higher than that of babies with either characteristic alone (15·42; 9·11-26·12).

Interpretation: Many babies in low-income and middle-income countries are SGA. Preterm birth affects a smaller number of neonates than does SGA, but is associated with a higher mortality risk. The mortality risks associated with both characteristics extend beyond the neonatal period. Differentiation of the burden and risk of babies born preterm and SGA rather than with low birthweight could guide prevention and management strategies to speed progress towards Millennium Development Goal 4--the reduction of child mortality.

Funding: Bill & Melinda Gates Foundation.

PubMed Disclaimer

Figures

Figure 1
Figure 1. The relation between birthweight and gestational age in Asia (A), Africa (B), and Latin America (C)
For Asian cohorts (A), percentages are for 78 048 infants. For African cohorts (B), percentages are for 38 948 infants. For Latin American cohorts (C), percentages are for 1 910 734 infants.
Figure 2
Figure 2. Relative risk of neonatal mortality associated with gestational age
Error bars are 95% CI.
Figure 3
Figure 3. Relative risk of neonatal mortality associated with small for gestational age
Figure 4
Figure 4. Relative risk of neonatal mortality associated with preterm and size for gestational age
Figure 5
Figure 5. Relative risk of early-neonatal, late-neonatal, and post-neonatal infant mortality associated with preterm and size for gestational age
See this image and copyright information in PMC

Comment in

References

    1. UNICEF. WHO. Low birthweight: country, regional and global estimates. New York: 2004.
    1. Lee ACC, Katz J, Blencowe H, et al. Born too small: national and regional estimates of term and preterm small-for-gestational-age in 138 low-income and middle-income countries in 2010. Lancet Glob Health. in press. - PMC - PubMed
    1. Kramer MS, Demissie K, Yang H, Platt RW, Sauvé R, Liston R, the Fetal and Infant Health Study Group of the Canadian Perinatal Surveillance System The contribution of mild and moderate preterm birth to infant mortality. JAMA. 2000;284:843–49. - PubMed
    1. Marchant T, Willey B, Katz J, et al. Neonatal mortality risk associated with preterm birth in East Africa, adjusted by weight for gestational age: individual participant level meta-analysis. PLoS Med. 2012;9:e1001292. - PMC - PubMed
    1. Narchi H, Skinner A, Williams B. Small for gestational age neonates—are we missing some by only using standard population growth standards and does it matter? J Matern Fetal Neonatal Med. 2010;23:48–54. - PubMed

Publication types