The purpose is to identify maternal and prenatal risks factors for placental vascular disorders. We excluded biologic and epidemiological data which are discussed in another chapter. Maternal risks factors are pre-existing vascular systemic diseases. Systemic lupus erythematosus (antiphospholipid antibodies are studied in another chapter) is a classical disease associated with unfavorable outcome, particularly when the disease is not quiescent and if the patient has a history of previous poor outcome. Obstetricians' awareness of the influence of inflammatory bowel diseases on pregnancy and fetal outcome is quite poor. These diseases, if they are not quiescent, can induce deleterious perinatal effects. Type 1 or even type 2 diabetes mellitus increases the risk of preeclampsia or hypertension in pregnancy, particularly when there is poor glycemic control early in pregnancy. The duration of type 1 diabetes affects the outcome of pregnancy more than type 2. Smoking during pregnancy is associated with many adverse events including spontaneous abortion, low birth weight and placental abruption. There are data about the dose-response relationship between the number of cigarettes smoked per day and the risk of abortion. Smoking during pregnancy is also protective against preeclampsia and this apparent paradox suggests the complexity of what is called vascular placental pathology. There is a significant relationship between pejorative perinatal vascular outcome and the non quiescence of renal disease. Mid-trimester uterine artery Doppler combining bilateral notches and increased uterine resistance index is the best criterion to predict the placental vascular risk of the pregnancy. Some promising studies suggest the feasibility of uterine Doppler ultrasound screening early in the pregnancy during the first trimester. Large studies are required to confirm this practice. Uterine artery Doppler in combination with other tests (elevated maternal serum hCG or ambulatory 24-hour blood pressure monitoring at 22 weeks gestation) could be a more efficient predictor of vascular complications. A large-scale evaluation is necessary before recommendations can be made. Multiple pregnancies increase the risk of preeclampsia 2- or 3-fold (RR 2.62; 95% CI: 2.03-3.38). A history of preeclampsia is the strongest predictor of unfavorable outcome for the second pregnancy.