<p>Advances in prenatal diagnosis create a unique set of clinical ethics dilemmas. Doctors routinely obtain genetic screening, radiologic images, and biophysical profiling. These allow more accurate diagnosis and prognosis than has ever before been possible. However, they also reveal a wider range of disease manifestations than were apparent when prenatal diagnosis was less sophisticated. Sometimes, the best estimates of prognosis turn out to be wrong. The infant's symptoms may be less severe or more severe than anticipated based on prenatal assessment. We present a case in which a prenatal diagnosis was made of severe osteogenesis imperfecta, leading to a decision to induce delivery at 31 weeks. On postnatal evaluation, the infant's disease did not appear to be as bad as had been anticipated. We discuss the ethical implications of such diagnostic and prognostic errors.</p>