INTRODUCTION: According to the Maternity Protection Act, an occupational risk of infection (e. g. in childcare) - combined with individual immunity gaps - can result in an irresponsible risk for pregnant women in the workplace. If this risk cannot be eliminated by any other means, the employer must impose a prohibition of employment (PE) for the pregnant woman concerned. We classified PE as preventable if the underlying immunity gaps could have been closed by immunisation prior to pregnancy. METHODS: From 01.09.2016 to 25.03.2020, 1922 pregnant employees of Bavarian state schools obtained medical counselling on their occupational risk of infection as part of a research project. If the individual combination of occupational-risk profile and immunity status resulted in an irresponsible risk for the pregnancy, a PE was recommended by the attending physician. We determined the proportion of PE that would have theoretically been preventable by full immunisation prior to pregnancy and approximated the resulting - theoretically preventable - loss of working hours and personnel costs. RESULTS: In 425 cases (22%), a PE was deemed necessary by the attending physician, whereby 193 (45%) were retrospectively classified as theoretically preventable. Of these cases, 53 PE (27%) were temporary (valid until the 20th week of pregnancy) and 140 were long-term (valid for the complete duration of the pregnancy). Based on these results, we approximated a loss of 2,746 working weeks for our collective, which entails theoretically preventable personnel costs totalling 5,763,305 € for the observation period of our study (3.6 years). We then extrapolated estimates for all employees of Bavarian state schools and found a loss of 4,260 working weeks and theoretically preventable personnel costs amounting to almost 8,941,000 € per year during our observation period. CONCLUSION: Theoretically preventable PE caused by immunity gaps can entail a considerable loss of working hours and high personnel costs. Therefore, we should step up measures aimed at improving vaccination rates in women and increasing their willingness to be vaccinated. In view of the changes in legal and regulatory conditions in Germany since 2020, new investigations should be made as soon as there is sufficient data after the general employment prohibitions due to the SARS-CoV-2-pandemic have been lifted.