Intrauterine growth restriction: no unifying risk factor for the metabolic syndrome in young adults.

BACKGROUND The validity and appropriateness of the metabolic syndrome as a cardiovascular risk factor are increasingly debated, partly because of the lack of a unifying underlying pathophysiological mechanism. Intrauterine growth retardation (low birth weight by sex and gestational length) has been associated with several cardiovascular problems and could be an important underlying risk factor for the metabolic syndrome. METHODS The association between intrauterine growth retardation (from the Norwegian Medical Birth Registry) and the metabolic syndrome in 7435 men and women aged 20-30 years from the population-based HUNT 2 study was studied with logistic regression using fractional polynomial models. RESULTS In men, there were significant associations with several of the separate components of the metabolic syndrome: central obesity (exponential, P<0.001), raised triglycerides (negative linear, P = 0.018), reduced HDL-cholesterol (U-shaped, P = 0.086), raised blood pressure (negative linear, P = 0.036), and impaired glucose tolerance (negative linear, P = 0.036). In women, there were significant associations with central obesity (positive linear, P<0.001) and raised blood pressure (negative linear, P = 0.003) but not with the other components. When combining these components into the metabolic syndrome, an exponential association was found in men (P = 0.017), that is, increased risk in patients with high birth weight only. In women, there was no association at all (P = 0.959). CONCLUSION Low birth weight was not associated with the metabolic syndrome at young adult age. Several associations between birth weight and the separate components of the syndrome were found, however, but these associations were partly in different directions.