Abstract
Nitric oxide (NO) production may be an important causal factor in hypertensive disorders during pregnancy. The plasma concentrations of NO2––+NO3––, stable metabolites of NO, were measured in 70 nonpregnant women, 323 normotensive pregnant women, 23 pregnant patients with preeclampsia, and 7 pregnant patients with essential hypertension. The normotensive women had higher plasma concentrations (30.0 ± 0.6 µmol/l) than nonpregnant women (18.3 ± 1.0 µmol/l; p < 0.0001). The plasma concentrations in the patients with preeclampsia (45.6 ± 2.3 µmol/l) were higher than in the normotensive women (30.3 ± 1.0 µmol/l; p < 0.0001) and were correlated with the systolic blood pressure (r = 0.442; p < 0.05). However, pregnant patients with underlying essential hypertension had significantly lower plasma concentrations (19.1 ± 3.0 µmol/l; p < 0.005). These findings suggest that NO contributes to maternal vasodilation, the maintenance of uterine quiescence, and the pathogenesis and clinical features of hypertensive disorders during pregnancy.