Measuring Babies' Oxygen Level During Labor May Lower Cesarean Rates
Feb. 3, 2000 (Miami) -- Cesarean deliveries are often done when the fetus is in distress during birth. Now a new device detects the amount of oxygen the fetus is receiving during labor and may help cut in half the rate of cesareans, according to Gary A. Dildy, MD, speaking here at a meeting of maternal-fetal medicine specialists. An FDA panel has recommended that the device be approved for use.
"Knowing the fetus' oxygen [level] takes some guesswork out of deciding whether to perform a cesarean vs. letting the labor progress," Dildy tells WebMD. He is an associate professor of obstetrics and gynecology at the University of Utah Health Sciences Center in Salt Lake City.
Monitoring the heart rate of the baby is an indirect way to assess the amount of oxygen in the blood, co-author Thomas J. Garite, MD, tells WebMD. This new device, which uses technology called pulse oximetry, assesses oxygen levels directly, according to Garite. Garite is a co-author of the study and professor and chair of obstetrics-gynecology at the University of California, Irvine.
The pulse oximetry device, known as the N-400, is placed through the cervix during labor. This device, which lies between the cheek of the fetus and the wall of the uterus, measures blood oxygen levels with a sensor that contains red and infrared light. The sensor is connected to a monitor that displays the fetus' current blood oxygen levels. Because of the risk of the device scratching the fetus' face, the device is not used if the mother is HIV-positive, as this would increase the chance of HIV being transmitted to the fetus.
The women in whom the device would be used are those who have already had fetal heart rate results that are considered nonreassuring. Although nonreassuring results are often false alarms, they are disconcerting to both the expectant parents and the physician and are typically a rationale for cesareans in which fetal distress is suspected.
In the current study, Dildy says there were 50% fewer cesareans performed for nonreassuring fetal status with the addition of the new device, compared to the women in which the device was not used. However, nonreassuring fetal status often results in difficult labor regardless, usually because of fetal size. Therefore, the group of women that used the device still had a larger than normal number of cesareans.
Not surprisingly, the FDA panel expressed concern that use of the device would extend to use beyond women with nonreassuring monitor results and, therefore, recommended that the manufacturer, Nellcor Perinatal Business, continue to study which patients undergo pulse oximetry once it is approved. The panel also required Nellcor to monitor whether use of the device became paradoxically associated with more cesarean births, possibly due to the reported increase in difficult childbirths.
The study was funded in part by Nellcor, a division of Mallinckrodt. Neither Dildy nor Garite has any direct financial relationship with the manufacturer, although Garite has been reimbursed for travel expenses when testifying to the FDA about the device.