ABSTRACT
The serum tetanus antitoxin was quantitatively measured in the blood of a group consisting of 358 healthy pregnant women and cord blood by ELISA. Only 3 percent of pregnant women before receiving immunization against tetanus had a protective level titre of 0.01 IU/ml or more. After 2 injections of 10 Lf absorbed tetanus toxoid, 95 percent of maternal blood and 90 percent of cord blood samples had a protective level titre. Antitoxin levels were directly related to the interval between injections. Two widely spaced injections, 6 weeks or more produced more protective results than 4 or 5 weeks intervals. Even though deliveries took place 1-3 weeks after a basic immunization course, 75 percent of cord blood had 0.1 IU/ml or more of serum tetanus antitoxin.