EARLY NUTRITIONAL ORIGINS OF HYPERTENSION - A HYPOTHESIS STILL LACKING SUPPORT

Purpose It has been hypothesized that limitations in 'a baby's nourish ment before birth: as reflected in reductions in birthweight and other newborn anthropometric measurements, are associated with subsequent e levations in blood pressure. We assess this hypothesis in light of fou r causal criteria commonly used by epidemiologists: specificity, consi stency, strength and biological coherence. We also examine aspects of the methodology used in studies of this hypothesis. Methodologic probl ems Two major data sources for testing the hypothesis in Hertfordshire and Preston are flawed by very high attrition. The practice of testin g this hypothesis by controlling for adult weight in the analysis over states the benefit that might accrue from interventions to increase bi rthweight. Causal criteria Studies used to support the hypothesis exam ine a wide variety of exposures and outcomes, without prespecification of which associations are expected. The inverse relationship of birth weight to blood pressure is found inconsistently and, when present is not strong. Potential confounding variables, especially social class, have not generally taken into account Evidence from human nutrition st udies, especially of famine exposure and pregnancy nutrition supplemen tation, are not supportive of the proposition that in industrialized c ountries variations in the birthweight of the population closely refle ct pregnancy nutrition. Conclusion When examined critically, the evide nce thus far provided does not support the hypothesis that prenatal nu trition is a major determinant of adult blood pressure.