Comment: This is an interesting study. I am perplexed by the minimal prolongation of the analgesia of sufentanil by the addition of morphine. Based on the results of this study I agree with the authors that there is little to recommend the addition of morphine, especially in view of the increased incidence of pruritus, nausea, and vomiting associated with its use.I am not surprised nor greatly concerned by the modest falls in blood pressure noted by the authors (not mentioned in the abstract). Epidural analgesia, with local anesthetics, has been shown to decrease circulating levels of epinephrine and norepinephrine in addition to decreasing the hyperventilation associated with painful contractions. Intrathecal fentanyl and sufentanil both quickly alleviate essentially all of the pain of labor and would be expected to result in the same effects minus the sympathetic block, associated with epidural local anesthetics. I doubt this modest fall in systolic blood pressure represents any significant threat to either the mother or the fetus.Lastly, I am somewhat at a loss to explain the enthusiasm of our colleagues for the use of sufentanil over fentanyl. The differences in onset time, intensity, and duration of analgesia between these two analgesics used intrathecally in equivalent doses (fentanyl 3.5:sufentanil 1) appears to be nil. Yet the cost differential is very great with 100 μg (2-ml ampule) of fentanyl costing $.23 compared with $10.18 for 50 μg (1-ml ampule) of sufentanil (the smallest dose available of each). Until this price differential decreases, this anesthesiologist can see little justification for the use of sufentanil for subarachnoid analgesia.