GDM affects maternal and fetal HDL composition and function. Changes are indicated with purple arrows. In maternal HDL, a decrease in PON1 activity and mass, apoM, and apoA-I content were observed, whereas SAA and LpPLA2 were increased. These changes in HDL composition were associated with reduced anti-inflammatory and anti-oxidative activity and reduced cholesterol efflux capacity. Fetal GDM-HDL showed the same alterations in PON1 and LpPLA2 activity, apoM and SAA content, and further increased apoE content. GDM was also accompanied by the increased particle size of both maternal and fetal HDL. HDL, high-density lipoprotein; apo, apolipoprotein; PON1, paraoxonase 1; LpPLA2, lipoprotein-associated phospholipase A2; SAA, serum amyloid A.