Infants are unable to make their own decisions or express their own wishes about medical procedures and treatments. They rely on surrogates to make decisions for them. Who should be the decision-maker when an infant’s biological parents are also minors? In this paper, we analyse a case in which the biological mother is a child. The central questions raised by the case are whether minor parents should make medical decisions on behalf of an infant, and if so, what are the limits to this decision-making authority? In particular, can they refuse treatment that might be considered best for the infant? We examine different ethical arguments to underpin parental decision-making authority; we argue that provided that minor parents are capable of fulfilling their parental duties, they should have a right to make medical decisions for their infant. We then examine the ethical limits to minor parents’ decision-making authority for their children. We argue that the restricted authority that teenagers are granted to make medical decisions for themselves looks very similar to the restricted autonomy of all parents. That is, they are permitted to make choices, but not harmful choices. Like all parents, minor parents must not abuse or neglect their children and must also promote their welfare. They have a moral right to make medical decisions for their infants within the same ‘zone of parental discretion’ that applies to adult parents. We conclude that adult and minor parents should have comparable decision-making authority for their infants.