Overview

Normal birthweight is critical to future health and development

Birthweight is a strong indicator not only of a birth mother's health and nutritional status but also a newborn's chances for survival, growth, long-term health and psychosocial development.

A low birthweight (less than 2,500 grams) raises grave health risks for children. Babies who are undernourished in the womb face a greatly increased risk of dying during their early months and years. Those who survive have impaired immune function and increased risk of disease; they are likely to remain undernourished, with reduced muscle strength, throughout their lives, and to suffer a higher incidence of diabetes and heart disease. Children born underweight also tend to have cognitive disabilities and a lower IQ, affecting their performance in school and their job opportunities as adults.

 

In the developing world, low birthweight stems primarily from poor maternal health and nutrition. Three factors have most impact: Poor maternal nutritional status before conception, short stature (due mostly to undernutrition and infections during childhood), and poor nutrition during pregnancy.

 

Inadequate prenatal weight gain in particular is a main cause of fetal growth retardation. Teenagers who give birth when their own bodies have yet to finish growing also have a greater risk of bearing underweight babies. Moreover, maternal diseases such as diarrhea and malaria, which are common in many developing countries, can significantly impair fetal growth.

 

Key interventions to prevent low birthweight, therefore, include improved food intake, micronutrient supplementation, preventing and treating diseases such as malaria and HIV/AIDS, educating girls and expectant mothers, and preventing teenage pregnancies.

Problems estimating low birthweight incidence

Some 60 per cent of newborns in developing countries are not weighed; in South Asia, which has the highest incidence of low birthweight babies, that figure is almost 75 per cent. Those newborns who are weighed, meanwhile, are probably better off -- more likely to be born in health facilities, urban areas and of better educated mothers -- which can lead to biased data.    

 

UNICEF and WHO have adjusted data from household surveys, such as DHS and MICS, for the underreporting and misreporting of birthweights. While these adjusted estimates represent an improvement over unadjusted estimates they may still underestimate the true magnitude of the problem. It is critical, therefore, that all babies be properly weighed at birth.

References

United Nations Children's Fund/World Health Organization, Low Birthweight - Country, Regional and Global Estimates, UNICEF, New York, 2004.      

 

MacDorman MF, Atkinson JO, Infant mortality statistics from the 1997 period linked birth/infant death data set. National Vital Statistics Report, 1999, 47 (23): pp. 1-23.

 

Barker, DJ (ed.), Fetal and infant origins of disease, BMJ Books, London, 1992.

 

Blanc, A and Wardlaw, T, Monitoring low birthweight: an evaluation of international estimates and updated estimation procedure, Bulletin of the World Health Organization, 2005, 83 (3): pp. 178 - 185.

 

UNICEF, Progress for Children, 2007.