Study: No benefit to fetal oxygen monitors

A large government study has concluded that monitoring fetal oxygen levels during labor does not lead to healthier newborns or reduce unnecessary Caesarean deliveries.

Fetal monitoring has long been controversial. Since the 1970s, doctors have routinely listened to fetal heartbeats despite no real evidence it did any good. In fact, some research found that it increased the number of C-sections by making doctors nervously reach for a scalpel whenever the monitor showed an abnormal blip.

New technology that measures oxygen levels in the blood of a fetus was thought to offer a better way to tell which babies were truly at risk. In 2000, the Food and Drug Administration conditionally approved one such device but required further study before allowing it into general use.

The study, published in today’s New England Journal of Medicine, was the biggest to date, involving more than 5,000 women, and was meant to be the definitive word. It was halted early because of overwhelming evidence that the technology was ineffective.

“There’s no reason to use it,” said lead author Dr. Steven Bloom, chief of obstetrics and gynecology at the University of Texas Southwestern Medical Center. “We didn’t find any evidence of harm, but why should we invest valuable health care dollars in something that doesn’t have a proven benefit?”

In an accompanying editorial, Dr. Michael Greene of Massachusetts General Hospital, who had no role in the research, noted that for once, an expensive technology can be stopped before it finds its way into widespread use. Fetal oxygen monitors are not part of routine care.

“This genie has not yet escaped from the bottle,” he wrote.

In fact, Pleasanton, Calif.-based Nellcor, which received FDA approval to market its OxiFirst devices, stopped selling them earlier this year because of a lack of demand, said company spokeswoman Kristin Garvin.

Garvin could not say how many fetal oxygen machines are installed in U.S. hospitals. In a news release 18 months after gaining FDA approval, Nellcor estimated that more than 400 devices have been used to monitor the births of about 9,000 U.S. babies.

Fetal oxygen machines are designed to be used with traditional electronic monitors, which track heart rate to determine if the fetus is experiencing stress or lacking oxygen.

In the study, doctors monitored the fetal oxygen levels in 5,341 women pregnant for the first time at 14 university hospitals in the United States. Once a woman’s water breaks, a sensor is inserted into her uterus and placed against the fetus’ temple or cheek. The sensor provides an up-to-the-minute reading of the fetus’ oxygen levels.

The fetal oxygen monitors cost about $10,000 each and the sensors about $150 apiece.

The women were then randomly separated into two groups. In one group, doctors could read the oxygen levels, while the information was hidden to the other group.

In both groups, about 26 percent of deliveries were done by C-section. Doctors also found no difference between the two groups in stillbirths, infections or other newborn problems.

The research was funded by the National Institute of Child Health and Human Development, part of the National Institutes of Health.