Longitudinal changes in PON1 activities, PON1 phenotype distribution and oxidative status throughout normal pregnancy

The purpose of the present study was to determine changes in plasma paraoxonase-1 activity (an indicator of paraoxonase phenotype) throughout normal pregnancy and its relationship with maternal oxidative stress status. The frequencies of the paraoxonase-1 phenotype in the studied population were determined using a two-substrate (paraoxon/diazoxon) activity method. As a parameter of oxidative stress status we measured the redox balance. Paraoxonase-1 activity significantly decreased at gestational week 32. In addition, the lipid profile was more atherogenic. Redox balance was significantly increased across gestational weeks. There were independent direct associations between maternal smoking habits before pregnancy, glucose concentrations and redox balance with PON1 activity in the third trimester. This study shows that pregnancy is followed by a decrease in PON1 activity and increased risk for development of cardiovascular diseases. We conclude that changes in paraoxonase-1 status during pregnancy are associated with maternal oxidative stress status and smoking habits.