Senescence varies across systems, species, model organisms and also dramatically among individuals.  The classic evolutionary theory of aging interprets physiological decline as a product of natural selection, where an organism will allocate resources to reproduction rather than somatic maintenance, as the aim is to pass on DNA. Yet, research so far has largely neglected the links between the evolution of aging and its selection on male and female reproductive strategies. There is research supporting that evolution has favored sex-specific life history strategies, e.g. for males “live fast, die young” and for females “live slow, die old”. However, focusing on the complex relationship between sex, pregnancy, mortality rate and aging is rare and remains poorly understood. My research focuses on pipefish and seahorses since they are part of the only vertebrate family (Syngnathidae) with paternal viviparity, providing me with the unique opportunity of decoupling the role of the female sex (defined as the contribution of eggs) and pregnancy (body reshaping and energy allocation), two traits usually found in females. This key feature makes them an important model organism for the study of sexual selection and aging.