Is there a moral obligation to select healthy children?

Reproductive decision-making in the post-genetic age is a minefield of complex ethical problems. One such problem centres on whether there is an obligation on reproducers to choose the best possible child. This paper focusses on a simplified scenario: there are two embryos to choose from, one of which will develop a condition that diminishes quality of life but would still have 'a life worth living', the other of which is normal. Is there an obligation to choose the healthier child? If so, what is the nature and scope of this obligation? The answer to these questions relies on a satisfactory answer to the non-identity problem (NIP). This paper explores several solutions to the NIP and argues for a solution grounded in the concept of harm. Various accounts of harm are discussed and synthesised to provide a new 'comparative bad state view' of harm. This account is used to justify the obligation to choose the healthier child. How far should this obligation go? This paper rejects the conservative position of 'procreative autonomy' - which holds that such obligations have no place in reproductive decisions - and the radical position of 'procreative beneficence' - which holds that there is an even stronger obligation to make the best possible child. The obligation to choose the healthier child may be over-ridden by countervailing reasons; the moral calculus in any individual case will be largely dependent on the expected quality of life of the child.