Pregnancies resulting in IUGR and also in preeclampsia are strongly associated with typical underlying placental pathology revealing small placentas and maldevelopment of the decidual blood vessels, suggesting under-perfusion from the maternal circulation. Since nitric oxide (NO) donors can improve decreased uteroplacental perfusion without any negative effects on fetal circulation, these may prevent negative pregnancy outcomes in patients at risk.

The aim of this study is to evaluate the effectiveness of the long-lasting NO donor pentarythrithyltetranitrate (PETN) to reduce the likelihood of adverse pregnancy outcomes (intrauterine growth retardation / IUGR, perinatal death, placental abruption, and preterm delivery) in women recognized to be at risk for this outcome by abnormal uterine flow in mid gestation.

Inclusion Criteria:

• pregnant women 190 to 236 weeks of gestation
• abnormal uterine Doppler as defined by bilateral notching, unilateral notching and increased impedance with mean resistance index (RI) > 0.65 or with mean RI > 0.7 without notching at time of enrollement
• informed consent

Exclusion Criteria:

• multiple gestation
• documented chromosomal or major fetal abnormalities
• rupture of membranes and/or clinical chorioamnionitis at time of enrolment
• maternal disease defined as contraindication for intake of PETN