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close this bookCauses and Consequences of Intrauterine Growth Retardation, Proceedings of an IDECG workshop, November 1996, Baton Rouge, USA, Supplement of the European Journal of Clinical Nutrition (International Dietary Energy Consultative Group - IDECG, 1996, 100 pages)
close this folderLevels and patterns of intrauterine growth retardation in developing countries
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View the documentDiscussion

Introduction

Intrauterine growth retardation (IUGR) constitutes a major clinical and public health problem in developing countries. Various criteria have been used to classify an infant as having experienced normal, subnormal, or supranormal growth in utero. Most recently a WHO Expert Committee (WHO, 1995a; de Onis and Habicht, 1996) recommended the 10th percentile of a birth-weight-for-gestational-age, sex-specific, single/twins risk curve (Williams et al, 1982) for the classification of small-for-gestational-age infants (SGA). Strictly speaking, SGA and IUGR are not synonymous (Altman and Hytten, 1989). Some SGA infants (e.g. those born to short mothers) may merely represent the lower tail of the 'normal' fetal growth distribution, while other infants who have been exposed to growth-inhibiting factors may actually meet the criteria for appropriate-for-gestational-age (AGA)(e.g. those born to tall, well nourished cigarette-smokers). In individual cases, however, it is usually very difficult to determine whether or not the observed reduced birth weight is the result of true in utero growth restriction, and classification is therefore based on the established cut-off for SGA. In fact, the higher the SGA rate, the greater the likelihood that SGA is a result of IUGR (WHO, 1995a). In this paper, for the purpose of being consistent with the terminology used in the Workshop, SGA infants will be referred to as IUGR.

Historically, because valid assessment of gestational age is often unavailable in developing countries, the incidence of low birth weight (LBW) has been often used as a proxy to quantify the magnitude of IUGR in these settings. This approach, however, underestimates considerably the overall magnitude of the IUGR problem as it does not take into account those infants whose weight at birth falls below the 10th percentile but who weigh more than 2500 g; many of these infants are likely to also have IUGR. Within these constraints, we make in this paper, for the first time, an attempt to quantify the magnitude and describe the geographical distribution of intrauterine growth retardation in developing countries. We use as the basis for the analysis, the incidence of infants born at term (³ 37 weeks of gestation) with low birth weight (< 2500 g), referred to as IUGR-LBW in this paper.