Technology for monitoring fetal oxygen during labor offers no apparent benefit

November 22, 2006

A new technology for measuring blood oxygen levels of a baby during labor--expected to provide information useful for preventing birth complications--offers no apparent benefit, report researchers in a National Institutes of Health research network.

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

"The results of this study show that while a new technology may appear to be very promising, it's not possible to know how effective it will be until it can be fully tested under clinical conditions," said Duane Alexander, M.D., Director of NIH's National Institute of Child Health and Human Development, which operates the network.

The study, appearing in the November 23 New England Journal of Medicine, was conducted by researchers in the NICHD Maternal-Fetal Medicine Units Network. The study's first author was Steven L. Bloom, M.D., of the University of Texas Southwestern Medical Center in Dallas.

"Fetal oxygen saturation monitoring offered no apparent advantage in interpreting the meaning of abnormal fetal heart rates," said Catherine Spong, M.D., an author of the study and Chief of NICHD'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 study authors noted that a technology developed earlier, electronic fetal heart rate monitoring, was adopted for use in delivery rooms without prior testing. Although electronic fetal heart rate monitoring is in widespread use, the study authors added, there is controversy about the technique's effectiveness.

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 open group and 2712 women were assigned at random to the masked group.

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 fetal heart rate and women experiencing dystocia. Again, the use of fetal oxygen saturation monitoring produced no statistically meaningful difference in Caesarean delivery for infants with a disturbance in fetal 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).

In 170 cases, the researchers were unable to position the sensor against the baby's face. In 40 cases, insertion of the sensor caused the baby's heart rate to slow down, potentially jeopardizing the ability to provide sufficient blood and oxygen to the tissues. The researchers theorized that such drops in heart rate might have been caused by inadvertent pressure on the umbilical cord when inserting the sensor, or because of manipulation of the baby's head.

"In this study of more than 5000 women delivering at 14 university hospitals throughout the United States, knowledge of intrapartum fetal oxygen saturation had no significant effect on the rates of Caesarean delivery overall or specifically for the indications of a nonreassuring fetal heart rate or dystocia," the authors wrote.
-end-
The NICHD sponsors research on development, before and after birth; maternal, child, and family health; reproductive biology and population issues; and medical rehabilitation. For more information, visit the Institute's Web site at http://www.nichd.nih.gov/.

The National Institutes of Health (NIH) -- The Nation's Medical Research Agency -- includes 27 Institutes and Centers and is a component of the U. S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical, and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit http://www.nih.gov

NIH/Eunice Kennedy Shriver National Institute of Child Health and Human Development

Related Heart Rate Articles from Brightsurf:

Women veterans with PTSD have higher rate of heart disease
Women veterans with posttraumatic stress disorder (PTSD) were 44% more likely to develop ischemic heart disease including heart attacks, compared to those without PTSD.

Flu vaccine rate less than 25% in young adults with heart disease, despite increased risk
In 2018, only about 25% of adults between the ages of 18 and 34 with any cardiovascular disease received a flu shot, and in those with a history of a heart attack, only about 20% were vaccinated.

Depression risk detected by measuring heart rate changes
For the first time doctors have shown that measuring changes in 24-hour heart rate can reliably indicate whether or not someone is depressed.

Death rate dramatically less for young heart attack survivors who quit smoking
Among young people who have had a heart attack, quitting smoking is associated with a substantial benefit.

Say no to vaping: Blood pressure, heart rate rises in healthy, young nonsmokers
New research finds that nicotine-filled e-cigarettes cause increases in heart rate and blood pressure in young people, health issues that remain even after a vaping session.

Heart rate measurements of wearable monitors vary by activity, not skin color
Biomedical engineers at Duke University have demonstrated that while different wearable technologies, like smart watches and fitness trackers, can accurately measure heart rate across a variety of skin tones, the accuracy between devices begins to vary wildly when they measure heart rate during different types of everyday activities, like typing.

Researchers report first recording of a blue whale's heart rate
With a lot of ingenuity and a little luck, researchers monitored the heart rate of a blue whale in the wild.

Pupil dilation and heart rate, analyzed by AI, may help spot autism early
Autism and other neurodevelopmental disorders often aren't diagnosed until a child is a few years of age, when behavioral interventions and speech/occupational therapy become less effective.

Heart rate variation due to stress affects auditory attention
Study shows that brain activity related to auditory perception parallels heart rate, offering new perspectives for the treatment of attention and communication disorders.

In HIE, lower heart rate variability signals stressed newborns
In newborns with hypoxic-ischemic encephalopathy, lower heart rate variability correlates with autonomic manifestations of stress shortly after birth, underscoring the importance of this reading as a valuable biomarker, according to Children's research presented during the Pediatric Academic Societies 2019 Annual Meeting.

Read More: Heart Rate News and Heart Rate Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.