Jeff McMahan, Professor of Philosophy at Rutgers University argues that, with our current medical knowledge, there are around four months where a foetus would survive if it were born prematurely. Therefore, the main difference between infanticide and abortion during that period is the geography of the foetus. There are stronger reasons for allowing abortion than infanticide; a foetus imposes a unique burden on one individual, the mother. Once born, on the other hand, the baby may be adopted or its care shared amongst a group of people. Nevertheless, it may be that in some rare cases infanticide can be morally permissible.