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Fetal Pulse Oximetry Does Not Alter the Rate of Cesarean Delivery

Such monitoring appears to be of no benefit as an adjunct to fetal heart-rate monitoring.

The introduction of intrapartum fetal heart-rate monitoring in the 1970s was believed to herald an era in which hypoxia during labor would become nonexistent. Three decades later, electronic fetal heart-rate monitoring has contributed to an increase in the rate of cesarean delivery, but there is no evidence that such monitoring has led to improved fetal outcomes.

Now, the FDA has approved an oxygen-saturation monitoring system intended to be used as an adjunct to electronic fetal monitoring to improve knowledge of the fetal condition before determining that cesarean delivery is necessary. To determine whether knowledge of fetal oxygen saturation affects the rate of cesarean delivery, researchers from the NIH’s Maternal-Fetal Medicine Network randomized more than 5300 nulliparous women in early labor at term to open fetal pulse oximetry (in which clinicians were aware of fetal oxygen saturation) or masked oximetry (in which they were not).

There were no significant differences between the two groups in rates of cesarean delivery (26.3% and 27.5%, respectively) or of forceps- or vacuum-assisted vaginal delivery. There also was no difference when the analysis was limited to women with "nonreassuring" fetal heart-rate patterns. Of note, 34.6% of nonreassuring patterns were associated with low oxygen saturation, but so were 25.1% of normal patterns.

Comment: This study provides strong evidence that fetal pulse oximetry is of no benefit as an adjunct to electronic fetal heart-rate monitoring.

— Robert W. Rebar, MD

Published in Journal Watch General Medicine November 22, 2006

Citation(s):

Bloom SL et al. Fetal pulse oximetry and cesarean delivery. N Engl J Med 2006 Nov 23; 355:2195-202.

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