This book examines the regulation and practice of medical decision-making where the context is that of a multiple pregnancy and where the question is whether or not to carry out a fetal reduction procedure. It concerns three main lines of inquiry: first, the nature of fetal reduction and the legal ground(s) for termination typically relied upon; secondly, the extent to which legal, ethical, and professional norms guide or constrain this particular kind of decision-making; and, thirdly, the adequacy of these norms. The book uses empirical sources to develop its analysis, contributing new insight and the kind of evidence necessary to shape regulation, clinical practice, and future research. The key findings show that fetal abnormality is often given as the justifying ground; that the legal, ethical, and professional norms offer little explicit guidance for fetal reduction: and on the general question of termination, ethical norms suffer from a high level of contestation, the key norms in the UK abortion legislation are unclear and disconnected from practice, and professional norms are only marginally more adequate. Given the indeterminacy of these norms, it is no surprise that the evidence indicates that doctors are only weakly guided by them in making their decisions. Various recommendations are advanced in this book, including the need for a situational emphasis on shared decision-making and patient-centred care.