We appreciate the interest in our Clinical Opinion. After thorough consideration of the data cited in both letters (some, if not most of which was specifically addressed in our Clinical Opinion) our stance remains unchanged. The routine exposure of 1.5-2 million parturients and their fetuses annually (in the United States alone) to an unproved intervention is not supported by the current literature. Although maternal oxygen administration may make physiologic sense, it is not enough: physiologic plausibility has led to the use of many obstetric interventions that have subsequently been proven not helpful and, in some cases, clearly harmful. Pregnant women and their offspring deserve care and interventions that, whenever possible, are based on better data than are currently available to justify intrapartum oxygen use for fetal benefit. Rather than sanguinely assuming that the benefits of oxygen are self-evident, properly designed clinical trials should be conducted to assess the potential benefits and risks of intrapartum oxygen.