The technology, known as foetal oxygen saturation monitoring, was designed for use along with electronic foetal monitoring, which tracks the foetal heart rate, to measure changes in foetal oxygen levels. Designers of the new technology hoped that knowing the oxygen status of the baby during labour would provide information on the health of the baby, especially when there were disturbances in the foetal heart rate during labour.

"Foetal oxygen saturation monitoring offered no apparent advantage in interpreting the meaning of abnormal foetal heart rates," said Catherine Spong, M.D., an author of the study and Chief of the National Institute of Child Health and Human Development 's Pregnancy and Perinatology Branch. "Abnormal oxygen readings were common among babies showing abnormal heart rates but they were also common among babies with normal heart rates."

The women enrolled in this study 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.

Overall, the researchers found no statistically meaningful differences in Caesarean delivery rates between the groups. In the open group, 26.3 percent of deliveries were by Caesarean, versus 27.5 in the masked group. The researchers also compared Caesarean rates for two subgroups in the study, babies experiencing a disturbance in foetal heart rate and women experiencing dystocia - failure of the baby to move down the birth canal.

Again, the use of foetal oxygen saturation monitoring produced no statistically meaningful difference in Caesarean delivery for infants with a disturbance in foetal heart rate, (7.1 percent for the open group, 7.9 percent in the masked group). Differences in Caesarean delivery rates for dystocia also were not statistically meaningful between the two groups (18.6 percent for the open group, 19.2 percent, for the masked group).

MEDICA.de; Source: National Institute of Child Health and Human Development