Abstract
The coagulation factors PP% (Factors II+IV), factor IX and factor X were determinated in infants born by mothers receiving anticoagulants. The factors were very low when the mothers did not receive vitamin K before the delivery. No significant improvement in the factors was observed after an intravenous or intraamniotic injection of vitamin K two to four days before the delivery. Vitamin K was injected intramuscularly into four foetuses in utero using an ultrasonic multitransducer scanner. Three of these infants had normal coagulation factors at birth. In the fourth case the factor X was normal and factor IX was significantly better than in the infants of the other groups. The injection had no harmful effects to the infants.