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Nevin S. Scrimshaw and Beat Schürch, Editors
Intrauterine growth retardation (IUGR) is a major public health problem in most developing countries. This special issue reports the proceedings of a workshop of the International Dietary Energy Consultancy Group (IDECG) that focused on the causes and consequences of being born with a low birthweight at term in a socio-economically deprived population. The role of nutrition in both the causation of IUGR and the exacerbation of its consequences make publication in the European Journal of Clinical Nutrition particularly appropriate. Moreover, important evidence for the lasting consequences of IUGR comes from a remarkable series of follow-up studies of individuals born with low birthweight in the UK earlier in this century and from other evidence based on studies of European populations malnourished in the past.
The causes of IUGR are multiple and interactive, and their relative importance varies with time, place and population. In developing countries, the major determinants of IUGR are nutritional (as reflected by low gestational weight gain, low pre-pregnancy BMI and short maternal stature), whereas in industrialized countries today cigarette smoking is by far the most important etiologic determinant, followed by low gestational weight gain and low pre-pregnancy BMI.
Some studies attempted to achieve a high internal validity by isolating single determinants as much as possible. Data of mothers and their offspring whose pregnancy coincided for some time with a famine in North Holland during the Second World War exemplify that position. They allow examining the consequences of undernutrition as the dominant determinant. Other studies that are more aimed at maximizing external validity and generalizability take into account several factors and their interactions. The workshop participants tried to draw inferences from both of these approaches.
IUGR is associated with impaired immunocompetence, increased morbidity and mortality in infancy and growth deficits persisting into adulthood. Neurological, cognitive and behavioral deficits appear to be most marked from the pre-school years through adolescence. A number of epidemiological studies have shown associations between low birth weight and earlier and higher prevalence of hypertension, coronary heart disease, adult onset diabetes, chronic respiratory disease, autoimmune thyroid disease and some forms of cancer. A systematic review of 126 available randomized controlled trials testing the efficacy of 36 kinds of prenatal interventions, provides strong evidence of benefit only for three of them: balanced protein/energy supplementation, strategies to reduce maternal smoking and antimalarial prophylaxis.
Working groups reviewed major topics and summarized the most important conclusions that could be derived from the discussions and information presented at the workshop, identified gaps in our knowledge and defined priorities in research needed to resolve persisting problems.
We are particularly indebted to the authors of the review papers. Several of them not only provided an up-to-date review of the literature but also spent many hours reanalyzing all available data sets. We are grateful to the United Nations University and the Nestle Foundation for funding this workshop, to Prof. George Bray and his collaborators at the Pennington Biomedical Research Center in Baton Rouge for providing the facilities and logistic support, and to Dr. Elisabeth Müller for her help in preparing the manuscripts for publication.
Nevin S.
Scrimshaw
Beat Schürch
October 10, 1997