This article focuses on maternal-fetal surgery (MFS) and on the concept of clinical equipoise that is a widely accepted requirement for conducting randomized controlled trials (RCT). There are at least three reasons why equipoise is unsuitable for MFS. First, the concept is based on a misconception about the nature of clinical research and the status of research subjects. Second, given that it is not clear who the research subject/s in MFS is/are, if clinical equipoise is to be used as a criterion to test the ethical appropriateness of RCT, its meaning should be unambiguous. Third, because of the multidisciplinary character of MFS, it is not clear who should be in equipoise. As a result, we lack an adequate criterion for the ethical review of MFS protocols. In our account, which is based on Chervenak and McCullough's seminal work in the field of obstetric ethics, equipoise is abandoned. and RCT involving MFS can be ethically initiated when a multidisciplinary ethics review board (ERB), having an evidence-based assessment of the risks involved, is convinced that the value of answering the research hypothesis, for the sake of the health interests of future pregnant women carrying fetuses with certain congenital birth defects, justifies the actual risks research participants might suffer within a set limit of low/manageable.