A study has cast doubt on the effectiveness of fetal monitors in preventing brain damage during childbirth, finding that 99.8 percent of all signs of such injuries turn out to be false alarms.
Electronic fetal monitoring is routine in hospital delivery rooms. Some critics contend monitoring often leads doctors to perform unnecessary Caesarean sections.The latest report shows that monitoring does an extremely poor job of achieving its primary goal, detecting fetal distress before it leads to brain damage.
Despite the new findings, some doctors contend monitoring is still worthwhile, particularly in pregnancies that are complicated by diabetes, high blood pressure, lupus and other conditions.
"I'm afraid this will lead people to think monitoring is unnecessary, high-tech interference," said Dr. John Repke of Brigham and Women's Hospital in Boston. "I don't think this information supports that notion."
Electronic monitoring provides an up-to-the-minute check of the emerging baby's health. Irregular heartbeats at this stage can be a sign of too little oxygen. When this happens, doctors assume that quick action - often an emergency Caesarean - will prevent brain damage resulting in cerebral palsy or retardation.
In the latest study, doctors from the National Institute of Neurological Disorders and Stroke reviewed the records of 155,636 babies born in California in the mid-1980s.
The results, published in last week's issue of the New England Journal of Medicine, show that in one sense, monitoring does work: Victims of cerebral palsy are more likely to have abnormal heartbeats during birth.
However, detecting these cases comes at a significant cost. "The false positive rate is exceedingly high," said Dr. Karin B. Nelson, the study's primary author.
She calculated that of every 100,000 babies monitored during birth, 9,300 will have abnormal heartbeats. Yet just 18 of these would be expected to have cerebral palsy.
Because of the false alarms, however, many of the 9,300 mothers would be rushed to the operating room for Caesarean sections. About 4 percent of these operations will have serious complications, such as bleeding and infection.
Furthermore, the study showed no benefit from the Caesarean deliveries. Among those with ominous fetal monitoring results, babies who were delivered surgically were just as likely to have cerebral palsy as were those who were delivered vaginally.
Nelson said fetal monitoring is so common that doctors are unlikely to abandon it, and she is not advocating that they do so.
"The possibility of saving the very occasional baby - the unproven benefit - has to be weighed against the clear-cut risk to very large numbers of people," she said. "I hope this will open a dialogue. It isn't the last word."