U-CaVIT Versus Standard of Care for Prevention of Atonic Postpartum Hemorrhage After Cesarean Section in High-risk Women.

Inclusion Criteria: * Signed informed consent * Maternal age ≥18 years * Gestational age ≥30+0 weeks of pregnancy at day of delivery * Vital pregnancy * Delivery mode: planned cesarean delivery * High-risk patient for PPH specified by the presence of at least one of the following characteristics: Previous PPH, obesity (BMI ≥30 kg/m2), high parity (patient who has had ≥4 previous births (live or stillborn) at ≥20 weeks of gestation), very advanced maternal age ≥45 years, multiple gestation, polyhydramnios (defined as amniotic fluid index \> 25 cm or deepest amniotic fluid pocket \> 8 cm) at admission to delivery, suspected fetal macrosomia (estimated fetal weight ≥ 4500g) Exclusion Criteria: * Insufficient language skills in German or English to understand and sign informed consent * Participation in another interventional study * Emergency cesarean section (incl. patients undergoing cesarean after failed vaginal delivery) * Subjects who change their delivery plan from vaginal to cesarean section in the course of hospitalization * Women with regular and painful contractions and women who do not have time for sufficient consideration * Clinical situations in which vacuum-induced uterine tamponade is unlikely to be effective or is contraindicated: * Uterine or vaginal anomalies (genital tract congenital anomalies) * Cesarean section due to placenta previa or suspected placenta accreta spectrum * Suspected uterine rupture * Injuries of the cervix or vagina * Submucous or intramural uterine fibroids which are buldging into the uterine cavity * Deep endometriosis \[16, 17\] * Planned atony-prophylaxis with oxytocin due to contraindication for carbetocin * Previous MMC-repair (myelomeningocele-repair) * Clinical diagnosis of chorioamnionitis, sepsis * Known allergy to silicone * Known and proven diagnosis of bleeding disorder or thrombophilia * Known thrombocytopenia during second half of pregnancy with thrombocytes \< 100 G/L * Known anemia during second half of pregnancy with Hb\<80