Effects of infant birthweight and maternal body mass index in pregnancy oncomponents of the insulin resistance syndrome in China

Background: Reduced birthweight is associated with increased risk for the i nsulin resistance syndrome. Part of this risk is hypothesized to originate from undernutrition in utero. The prevalence of the insulin resistance synd rome increases in countries that undergo the transition from chronic malnut rition to adequate nutrition, when postnatal nutrition improves more rapidl y than prenatal nutrition. Objective: To determine whether the components of the insulin resistance sy ndrome are associated with reduced fetal growth and maternal undernutrition . Design: A nonconcurrent, prospective study of men and women whose mothers' heights and weights were recorded during pregnancy. Setting: Beijing, China. Participants: 627 men and women (mean age, 45 years) whose mothers' obstetr ic records were preserved. Measurements: Adult offspring's blood pressure, plasma glucose levels, insu lin levels, and lipid concentrations during an oral glucose tolerance test. The main explanatory measurements were mothers' body mass index during pre gnancy and offspring's birthweight and adult size. Results: After adjustment for sex and current body mass index, low birthwei ght was associated with elevated plasma glucose levels, insulin levels, tri glyceride concentrations, and blood pressure. For every l-kg increase in bi rthweight, systolic blood pressure decreased by 2.9 mm Hg (95% CI, 0.3 to 5 .4 mm Hg) and the 2-hour plasma glucose level decreased by 5.1%(CI, 0.7% to 9.3%). Low maternal body mass index in early and late pregnancy was associ ated with elevated levels of plasma glucose, insulin, and triglycerides in adult offspring but was not associated with elevated blood pressure. Conclusions: Risk for the insulin resistance syndrome may be partially esta blished through low maternal body mass before pregnancy and consequent feta l undernutrition. This risk is independent of that associated with adult ob esity. In developing countries such as China, improved nutrition in girls a nd young women may offer long-term benefits to offspring.