Conception of a child using cryopreserved sperm from a deceased man is generally considered ethically sound provided explicit consent for its use has been made, thereby protecting the man's autonomy. When death is sudden (trauma, unexpected illness), explicit consent is not possible, thereby preventing posthumous sperm procurement (PSP) and conception according to current European Society of Human Reproduction and Embryology and the American Society for Reproductive Medicine guidelines. Here, we argue that autonomy of a deceased person should not be considered the paramount ethical concern, but rather consideration of the welfare of the living (widow and prospective child) should be the primary focus. Posthumous conception can bring significant advantages to the widow and her resulting child, with most men supporting such practice. We suggest that a deceased man can benefit from posthumous conception (continuation of his 'bloodline', allowing his widow's wishes for a child to be satisfied), and has a moral duty to allow his widow access to his sperm, if she so wishes, unless he clearly indicated that he did not want children when alive. We outline the arguments favouring presumed consent over implied or proxy consent, plus practical considerations for recording men's wishes to opt-out of posthumous conception.