OW BIRTH WEIGHT IS ASSOCIated with cardiovascular risk factors and death in adulthood. 1 Differences in the size, molecular weight, composition, and quantity of lipoprotein subclasses are associated with coronary artery disease (CAD). 2 In our initial study of lipoprotein heterogeneity in cord blood, infants born small for gestational age (SGA) had higher levels of triglyceriderich very low-density lipoprotein (VLDL) and intermediate low-density lipoprotein (IDL) than infants born appropriate for gestational age. 3 This finding extended the observations of others in SGA infants 4-7 and suggested a link between higher triglyceride-rich VLDL subclasses in SGA infants and future CAD. We assessed a large high-density lipoprotein (HDL) subclass in cord blood 8-15 enriched in apolipoprotein C-I (apo C-I). Apolipoprotein C-I is a 6.6-kDa apolipoprotein, and in adults it is a component of VLDL, IDL, and HDL. 16 Apolipoprotein C-I displaces apo E from VLDL and IDL, thereby decreasing their clearance from plasma. 17 Apolipoprotein C-I decreases the binding