Preeclampsia (PE) and fetal growth restriction (FGR) contribute significantly to fetal and maternal morbidity and mortality. Although the causes of PE and FGR are not fully understood, both conditions are known to be associated with impaired uterine artery blood flow. Resveratrol, a polyphenol found in a number of plants, has been shown to induce relaxation of uterine arteries in vitro as well as improve many pathological conditions associated with PE and FGR. We hypothesized that treatment of endothelial nitric oxide synthase knockout mice (eNOS^−/−) and catechol-O-methyltransferase knockout mice (COMT^−/−) with resveratrol during pregnancy would improve uterine artery blood flow and therefore ameliorate the PE-like phenotype and FGR in these murine models. Pregnant C57BL/6J, eNOS^−/− and COMT^−/− mice received either resveratrol supplemented diet (4 g/kg diet) or control diet between gestational day (GD) 0.5 and GD 18.5. Resveratrol supplementation significantly increased uterine artery blood flow velocity and fetal weight in COMT^−/− but not in eNOS^−/− mice. There were no effects of resveratrol on litter size and placental weight among the groups. In conclusion, resveratrol increased uterine artery blood flow velocity and fetal weight in COMT^−/− mice, suggesting potential as a therapeutic strategy for PE and FGR.