Adult BMI and fat distribution but not height amplify the effect of low birthweight on insulin resistance and increased blood pressure in 20-year-old South Africans

We examined whether associations between low birthweight and adult chronic cardio-metabolic disease were dependent upon birthweight alone, or on interactions with BMI, fat accumulation either generally or abdominally, or attained height in young South African adults. Blood pressure (BP), lipids, glucose tolerance, insulin sensitivity and secretion (homeostasis model) were measured in 20-year-olds (n=132) born at full term and with birthweights on or below the tenth centile (underweight for gestational age [UFA]) or between the 25th and 75th centiles for gestational age (appropriate weight for gestational age, [AFA]). Sex-specific median measurements of BMI, waist circumference, percentage body fat and height defined current anthropometric status, providing four groups for each measure: UFA-low or UFA-high and AFA-low or AFA-high. The UFA-high BMI group was more insulin-resistant than both low BMI groups (p < 0.04), but not the AFA-high BMI group. In contrast, plasma triglycerides and systolic BP were higher in the UFA-high than in all other groups (all p < 0.04). When characterised by body fatness, both high percentage (%) body fat groups had higher fasting [insulin] than low percentage (%) body fat groups (p < 0.03), and higher [total cholesterol] and [LDL cholesterol] than the UFA-low percentage (%) body fat group (p < 0.05). The UFA-high group had higher systolic and diastolic BP than all other groups (all at least p < 0.03). A similar pattern was observed when groups were characterised by waist circumference; however, current height status had no effect. These data indicate that the "fetal origins" expression of the chronic disease phenotype is not dependent on birthweight alone, but on its interaction with subsequent fat accumulation, though not on attained height, in this cohort of young adults.