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The Truth About Electronic Fetal Heart Rate Monitoring

Little evidence backs the use of the nearly universal childbirth practice of electronic fetal heart rate monitoring. But it does lead to more C-sections.

When it comes to your birth plan, it can feel like there are thousands of decisions to make. Luckily, some childbirth practices are so common that they’re basically a given. That’s the case for electronic fetal heart monitoring (EFM), which continuously tracks the baby’s heart rate and contractions during labor and delivery. Using monitors strapped to the pregnant person’s abdomen, EFM is used in nearly 90 percent of all hospital births in the US. But despite their widespread use, some experts say there’s not enough evidence to support electronic fetal heart monitoring for low-risk births — and that overusing them leads to unnecessary C-sections.

EFM entered hospitals in the 1970s after a big push from the monitoring industry — but with no clinical trials proving that they’re safe and effective. At the time, there were other methods of tracking the baby’s heart rate and rhythm during childbirth. But EFM had an advantage over the others: It would bring an end to cerebral palsy. Or so the industry claimed. But EFM was entirely experimental — a fact unknown to the many women it was used on.

Since then, researchers have investigated whether there’s a connection between EFMs and cerebral palsy, but they’ve come up empty-handed so far. There is no difference in cerebral palsy rates between EFM and hands-on listening, the second most popular method of fetal heart monitoring, according to a review from Cochrane, a trusted network of researchers, that analyzed results from more than 37,000 participants. Hands-on listening, also known as auscultation, is only performed at certain intervals throughout childbirth and gives the pregnant person more flexibility and comfort.

Pregnant people who use continuous EFM instead of hands-on listening are 63 percent more likely to have a C-section.

Frankly, it’s not surprising that EFM hasn’t been linked to lower cerebral palsy rates. It’s a poor test for risk of the condition — not because it misses cases, but because it often flags perfectly normal labor as risky, with false-positive rates as high as 99.8 percent. In other words, almost every time an EFM signals that a fetus is at risk for cerebral palsy, it’s wrong.

EFM doesn’t protect against other negative outcomes either. Compared to hands-on listening, there is no difference in babies’ Apgar scores or cord blood gases, rates of low-oxygen brain damage, admission to the neonatal intensive care unit, or perinatal death, according to the Cochrane review. That’s true for both high- and low-risk pregnancies.

There is one major benefit of EFM: It can reduce seizures. Newborns delivered with continuous EFM were 50 percent less likely to have seizures than those in the hands-on listening group, according to the review. For some experts, that’s enough of a reason to keep using EFMs. But the seizure evidence itself comes mostly from the 1970s and 1980s when labor practices were very different.

The overall risk of newborn seizure is small no matter how nurses listen to the baby’s heart. The seizure risk is 0.15 percent for newborns of parents that underwent continuous EFM and 0.30 percent for those delivered with hands-on listening. As many as 667 pregnant people would have to use continuous EFM to prevent one seizure. And if that weren’t enough, researchers haven’t investigated whether newborn seizures harm the baby’s health in the long run.

“The more we use electronic fetal monitoring, the more harm we do, with little evidence of benefit.”

If there weren’t any negative consequences of EFM, it might make sense to use it to reduce the small risk of newborn seizures. But the technique is not without its own problems, namely that it leads to unnecessary C-sections.

“The findings of normal fetal heart rate in labor are very reliable and say that the fetus is tolerating the stresses of labor without challenge,” says Michael Nageotte, the director of maternal/fetal medicine at Long Beach Medical Center. “More importantly, perhaps, is that when it is not normal, which is very common, that doesn’t necessarily mean there’s anything wrong with the baby. It’s just that your level of confidence may be less.”

The American College of Obstetricians and Gynecologists lists “non-reassuring fetal heart tones” as the second leading cause of first-time C-sections in the U.S. Pregnant people who use continuous EFM instead of hands-on listening are 63 percent more likely to have a C-section, according to the Cochrane review. The reviewers estimate that for every 11 births using EFM, there is one additional C-section. For every one seizure prevented by EFM, there are 61 unnecessary C-sections.

C-section, a major surgery, carries risks that vaginal birth does not. The parent delivering the baby may develop reactions to anesthesia, blood clots, and infection in the incision or in the lining of the uterus, according to the Mayo Clinic. Babies delivered this way are more likely to have breathing problems. The parent will likely need C-sections for subsequent pregnancies because of the risk of serious complications. Yet multiple C-sections increase the risk of placental problems and heavy bleeding that can require a hysterectomy.

Childbirth with EFM also has a 15 percent higher risk of forceps or vacuum delivery. In forceps delivery, the doctor guides the baby’s head out with forceps, which are like salad tongs. This causes an increased risk of pain in the tissue between the vagina and anus after delivery, tears in the lower genital tract, trouble urinating, incontinence, injuries to the bladder or urethra, and tearing of the uterine wall. The baby will have an increased risk of conditions including skull fracture and seizure. Vacuum extraction guides the child’s head out with a vacuum pump and has some of the same risks as forceps delivery.

“The more we use electronic fetal monitoring, the more harm we do, with little evidence of benefit,” Peter Brocklehurst, professor of women’s health at Birmingham Clinical Trials Unit, said in a press release.

A less scientific argument against continuous EFM is that it’s just plain uncomfortable. One mother told ACOG, “The worst part was that the monitor took the focus off of me and put it on the machine. Every time I rolled over or tried to get comfortable, a nurse would come rushing in insisting that she’d lost the signal and that my baby could be in distress and I had to stop moving so much… It created a situation where I was a liability and a problem just for wanting to be the tiniest bit mobile.”

When it comes to deciding between EFM and hands-on listening, the choice is not the same for all pregnant people. Hands-on listening may not be safe for people with high-risk pregnancies, such as those with meconium staining, bleeding during labor, suspected fetal growth restriction, preeclampsia, prior C-section, type 1 diabetes, or who take the drug Pitocin, according to ACOG.

For everyone else, the choice comes down to how you weigh the risk of newborn seizures against the risk of C-section. If you don’t want continuous EFM, hands-on listening isn’t the only alternative. Another popular option is to use EFM periodically, at certain points throughout childbirth. Nageotte recommends asking your delivery team about their experience with EFM and hands-on listening before making a decision.

Despite the lack of evidence for continuous EFM, Nageotte doesn’t think it’s going away anytime soon. Hands-on listening is too time-consuming — one of the reasons why EFM became so widespread in the first place. “Because of the ability to free up the nurse from the labor-intensive auscultation performance, most hospitals by far in this country continue to use electronic fetal monitoring,” Nageotte says. “I think we’ll continue to use it into the future.”