Evidence-based hematological precautions for pregnant women incorporate several aspects. The purpose of the early discovery of a latent or pre-existing anemia and systematic iron supplementation is to achieve target hemoglobin concentrations of 120–135 g/l at parturition in order to reduce the probability of peripartal transfusion. The detection of a hemoglobinopathy requires genetic counseling if both parents are carriers. The determination of blood groups and irregular blood group antibodies allow a timely recognition of transfusion difficulties and if necessary rhesus anti-D prophylaxis to avoid sensitization. Finally, the detection of an increased tendency to hemorrhage or thrombosis allows targeted measures to reduce the risks, e.g. a long-term prophylaxis with low molecular weight heparin for thrombophilia and for disorders of plasma clotting or platelet function the probability of postpartal hemorrhage can be reduced by specific measures. In multiple pregnancies determination of the chorionicity and amnionicity in the first trimester, ideally between 8 and 10 weeks of gestation, lays the foundations for the subsequent care, either with or at a perinatal center. In addition to measurement of nuchal translucency, a fetal DNA test can be provided as a prenatal non-invasive screening. Sonographic screening for malformations should be carried out between 18 and 21 weeks of gestation. Measurement of cervical length at 22–24 weeks of gestation can be used to estimate the risk of premature birth. After 16 weeks of gestation ultrasound control examinations should be carried out every 2 weeks for monochorionic multiple pregnancies and for inconspicuous dichorionic multiple pregnancies this is possible at intervals of 3–4 weeks for growth control. Preeclampsia must be excluded at every pregnancy control by blood pressure measurements and urine tests. The occurrence of anemia, gestational diabetes and with intense itching, cholestasis of pregnancy must be clarified.