The authors of the current study undertook their research to try to find if there was sufficient reason to warrant introducing fetal oxygen saturation monitoring into the delivery room. A previous study of the technology was inconclusive. That study found no overall change in Caesarean delivery rates when fetal oxygen saturation monitoring was undertaken. However, the study found different rates of Caesarean deliveries for two different categories of births. For cases in which the fetal heart rate pattern was abnormal, there were fewer Caesarean deliveries than normal. But there was a higher-than-normal rate of Caesarean deliveries from cases involving dystocia--failure of the baby to move down the birth canal. (Dystocia can result from such causes as the baby being improperly positioned in the birth canal, or from the baby simply being too large.)
Because the results of that earlier study were inconclusive, the U.S. Food and Drug Administration, which approves new medical devices for safety and effectiveness, granted only provisional approval for fetal oxygen saturation monitoring until the new technology could be proven effective. The current study was designed to settle unresolved questions about the new technology.
With fetal oxygen saturation monitoring, a sensor is inserted by hand through the cervix, after the membranes have ruptured, and placed against the baby's face. The sensor, connected to a monitor by a cable, provides a continuous reading of the baby's oxygen level.
For the current study, the researchers enrolled 5341women from 14 hospitals throughout the United States. The women were randomly assigned to one of two groups: an "open" group, in which oxygen levels were continuously monitored, and a "masked" group, in which oxygen levels did not appear on a monitor and were not revealed to birth attendants. Of the pregnant women who participated, 2629 were randomly assigned to the
Source:NIH/National Institute of Child Health and Human Development