full term, in contrast to only 66.7% of the non-vaccinated patients. Preventive lactobacillus vaccination with Gynevac was performed on 1396 healthy women, partly before conception and partly during early pregnancy. The reported incidence of low birth weight was 7.9% among vaccinated women compared to 14.0% among healthy controls. In a subsequent prospective study with the participation of 1852 vaccinated pregnant women and 1418 controls, Lázár and coworkers reported a preterm birth rate of 7.1% among vaccinated women and 12.2% among those that declined lactobacillus vaccination. Formulation Each ampoule of Gynatren contains at least inactivated microorganisms of eight Lactobacillus strains in approximately equal amounts ( microorganisms per strain). Three strains belong to the species L. vaginalis, three strains to L. rhamnosus, one strain to L. fermentum and one to L. salivarius. The eight specific aberrant polymorphous Lactobacillus strains have been deposited at the Westerdijk Institute (Centraalbureau voor Schimmelcultures) in 1977 under the strain numbers CBS 465.77 to CBS 472.77. Inactivated material from the eight strains is mixed and diluted with physiological sodium chloride solution. Phenol is added as a preservative. The vaccine usually has a total nitrogen content of 3.68 mg in 100 ml solution (based on the dry material, using the Kjeldahl method). Using the conversion factor of 6.25 to convert nitrogen concentration to protein concentration, this means that there is on average 0.115 mg bacterial proteins in each ampoule of 0.5 ml. Gynevac is composed of five specific aberrant polymorphous Lactobacillus strains, four belonging to the species L. fermentum and one to the species L. reuteri. The further ingredients are formaldehyde and sodium ethylmercuric thiosalicylate (Thiomersal) as preservatives and sodium chloride solution as a diluent. Each ampoule of 1 ml contains between 0.08 mg and 0.32 mg bacterial proteins. Schedule The usual vaccination schedule of Gynatren is 3 intramuscular injections of 0.5 ml vaccine at intervals of 2 weeks, followed by a booster dose of 0.5 ml 6–12 months after the first injection. The booster injection raises the serum antibody titres in most cases back to similar levels to those found shortly after primary vaccination and ensures renewed immune protection for about 2 further years. Grčić et al. recommends the periodic administration of booster doses every 2 years to maintain protective immunity for many years. The schedule of Gynevac includes 5 intragluteal injections of 1 ml vaccine at intervals of 10 days. Protective immunity is conferred for about a