Teenage pregnancies have been considered mainly as perinatological and social problem up to now, in contrast biological and evolutionary aspects were neglected. In the present analysis the hypothesis is discussed that teenage pregnancies may represent a fitness maximizing strategy, with other words an efficient use of the relatively short female reproductive span. Results from auxology, primatology, historical demography and life history research, however, are in contradiction to the hypothesis. Extremely early teenage pregnancies (below the 16th birthday) seem to be a recent phenomenon caused by the decline of sexual maturation in course of the well described secular acceleration trend.