The duration of the presence of maternal mumps antibodies in a prospective cohort study is presented. Immunoglobulin G against mumps was portioned with a commercial ELISA test (Euroimmun(R) anti-mumps Virus AT ELISA, Germany) on samples from 213 mother-child pairs at seven time points between pregnancy and 12 months of age. Non-linear mixed models were used to model maternal antibody decay in infants. The model-based median time to loss of antibodies was 3.6 months. The median child-specific time to loss of antibodies in children of naturally immune women (3.8 months) and children of vaccinated women (2.4 months) differed significantly (p = 0.025). The log antibody level of the mother and the log birth weight were correlated with the duration of maternal antibodies in infants (p < 0.0001). Conclusion: Children of vaccinated women loose maternal mumps antibodies significantly earlier in life compared to children of naturally infected women. If early administration (<12 months) of the combined measles, mumps, and rubella vaccine is needed, maternal mumps antibodies are not expected to interfere with infant humoral vaccine responses