The aim of our study was to investigate the anti-tetanus and anti-diphtheria antibody titres and the placental transfer of these antibodies in a group of vaccinated and unvaccinated mothers and their term or preterm offsprings. Anti-tetanus and anti-diphtheria toxoid IgG antibodies were measured quantitatively by ELISA in 91 infant-mother pairs. Protective concentrations of anti-tetanus and anti-diphtheria were found in 58.3 and 50% of mothers in the unvaccinated group and 94.5 and 85.5% of the mothers in the vaccinated group. Protective concentrations were found in 63.9 and 50% of cord samples, respectively, in the unvaccinated group and in 96.4 and 85.5% of cord samples, respectively, in the vaccinated group (p = 0.0001). There were no differences in the maternal and cord geometric mean concentrations (GMCs) of anti-toxoid antibodies between those who received two doses or one dose of Td. The GMCs of maternal and cord anti-tetanus and anti-diphtheria were statistically similar between preterm and term groups. Placental transfer ratios (TR) for anti-tetanus and anti-diphtheria were 175 and 150%, respectively, in the preterm group and 213 and 178%, respectively, in the term group. There was a strong correlation between maternal and cord anti-toxoid antibody levels. Maternal vaccination was the only predictor of having protective concentrations of anti-toxoid antibodies in cord blood.
Conclusions: Vaccinating pregnant women with at least one dose of Td would confer protection for both the term and preterm infant-mother pairs. Therefore, health personnel caring for pregnant women have the responsibility to emphasize the importance of Td vaccination to avoid missed immunization opportunities.