Association of midgestational paraoxonase 1 activity with pregnancies complicated by preeclampsia

The antioxidant enzyme paraoxonase 1 is a marker of oxidative stress and has been implicated in the pathogenesis of preeclampsia. Our objective was to determine if an association exists between low paraoxonase 1 activity at midgestation and the development of preeclampsia. We conducted a case-control study of 50 women with preeclampsia and 101 women with uncomplicated term deliveries. Maternal serum collected at 15 to 20 weeks was used to measure paraoxonase 1 activity using two substrates: paraoxon and phenylacetate (arylesterase activity). The groups did not differ with respect to maternal demographics. Paraoxonase 1 activity (paraoxon) was significantly higher in women with preeclampsia compared with controls (19.4 +/- 9.4 versus 15.6 +/- 8.0 change in absorbance per minute (dA/min), P = 0.009). When stratified by disease severity, paraoxonase 1 activity (paraoxon) was highest in women with severe preeclampsia (21.6 +/- 9.1 versus 15.6 +/- 8.0 dA/min, P = 0.002). We observed a trend toward higher arylesterase activity in women with preeclampsia compared with controls (0.343 +/- 0.07 versus 0.323 +/- 0.06 dA/min, P = 0.06). Midgestational paraoxonase 1 activity is higher in women with preeclampsia before clinical signs of the disease are present. Prospective studies are needed to determine the significance of paraoxonase 1 in the pathogenesis of preeclampsia.