Aims/hypothesis: The association between lower birthweight and metabolic syndrome may result from fetal undernutrition (fetal programming hypothesis) and/or genes causing both low birthweight and insulin resistance (fetal insulin hypothesis). We studied associations between the birthweight of parents and metabolic syndrome in the offspring.
Methods: We identified men and women (aged 35-68 years), who had been born in Holdsworth Memorial Hospital, Mysore, India. We also identified the offspring (20-46 years) of these men and women. In total, 283 offspring of 193 mothers and 223 offspring of 144 fathers were studied. Investigations included anthropometry, oral glucose tolerance, plasma insulin and lipid concentrations and blood pressure. The metabolic syndrome was defined using WHO criteria.
Results: Among the offspring, lower birthweight was associated with an increased risk of glucose intolerance (impaired glucose tolerance, impaired fasting glucose or type 2 diabetes) and higher cholesterol and triacylglycerol concentrations (p < 0.05 for all adjusted for sex and age). Most outcomes in the offspring, including most individual components of the metabolic syndrome, were unrelated to parental birthweight. However, both maternal and paternal birthweight were inversely related to offspring metabolic syndrome (odds ratio [OR] 0.36 [95% CI: 0.13-1.01] per kg, p = 0.053 for mother-offspring pairs; OR 0.26 [0.07-0.93], p = 0.04 for father-offspring pairs, adjusted for offspring age, sex, BMI and socioeconomic status). Maternal birthweight was inversely related to offspring systolic blood pressure (beta = -2.5 mmHg [-5.00 to 0.03] per kg maternal birthweight; p = 0.052).
Conclusions/interpretation: Factors in both parents may influence the risk of metabolic syndrome in their offspring. There are several possible explanations, but the findings are consistent with the fetal insulin (genetic) hypothesis.