What is Electronic Fetal Monitoring (EFM)?
EFM monitors the baby’s heart rate and the mother’s contractions during labor, and alerts medical staff to any distress. The most common method of EFM is placing two receivers, held in place with two elastic belts, on the mother’s abdomen. A less common form of EFM involves inserting a receptor into the baby’s scalp.
What does the evidence suggest about its practice?
Despite numerous studies on the matter, no benefit has been found from the routine use of EFM technology.  There has been no reduction in infant deaths or cerebral palsy, which was the technology’s intended (and advertised) benefit.  Because of this, as well as the documented risks of the practice, both the World Health Organization (WHO) and the US Department of Health and Human Services (DHHS) recommend against continuous electronic fetal monitoring.  The technology has never been reviewed by the Federal Drug Administration for safety or efficacy. 
How is EFM currently used?
EFM is currently used in almost every birth in the United States, as much as 93% of the time. Some hospitals require at least a 20-minute observation upon admission to check the health of the baby. 
What are the risks?
Continuous use of EFM has repeatedly been linked to higher rates of intervention, including instrumental delivery and c-section, which carry their own set of risks.  There is a slight increase in the rate of infection to the baby, especially when an internal monitor is used, but these are typically mild and easily remedied. The patterns on the print out are open to the interpretation of the hospital staff, which frequently leads to misdiagnoses (this is called a “high false positive rate,” and is a sign of unreliability). 
In addition to its questionable benefit and documented risks to both mother and baby, the use of EFM has been shown to reduce the quality of care — women complain that the machine becomes the central focus of medical staff and birth attendants, rather than the laboring woman herself. Movement can cause the machine to malfunction, so the woman is confined to labor in bed on her back, a position that is shown to be more painful and less effective for labor to progress.
What is the alternative?
Intermittent listening with a Doppler or fetoscope has been shown to be just as effective at detecting fetal distress as constant monitoring, while at the same time reducing the risk of instrumental delivery and c-sections due to a “fetal distress” diagnosis.  This is the method recommended by the World Health Organization.
Electronic fetal monitoring has been accepted as a normal part of maternity care in the United States, despite any evidence of its benefit to the laboring woman and her baby. And while it provides the appearance that an individual is receiving continuous care, it has in fact made it possible for medical staff to care for more patients simultaneously, meaning a lower standard of care for each patient. Its high false positive rate means that more women are being subjected to unnecessary interventions and surgery because of the misdiagnosis of “fetal distress.” By confining women to bed, EFM makes labor more painful and less effective than if the woman was allowed freedom of movement. Despite claims that it would improve outcomes for mothers and babies, EFM has repeatedly shown NO benefit to either, after 30 years of research. So WHY IS IT STILL BEING USED??
Conspiracy theory time:
EFM has become so normalized that it is frequently used as evidence in malpractice lawsuits, which is why many hospitals now mandate its use — it is their paper trail.  EFM gives the illusion of accuracy, but is in fact open to interpretation much of the time, hence its high rate of inaccuracy. Without it, doctors and hospitals would be more vulnerable to lawsuits, but with EFM they can justify their choices.
EFM is a multimillion dollar technology, whose makers implied that a perfect outcome was possible with its use. Its widespread adoption reduces costs to hospitals by making it possible to care for more laboring women simultaneously, but the resulting interventions (such as c-section) actually make birth more expensive for patients. Is it possible that those that stand to benefit financially (the EFM industry and the hospitals that use it) are pushing for its continued use? Is it possible that these groups are more concerned about their bottom line than what is best for you and your baby?
You have the right, as a patient, to refuse any procedure, including EFM. You can request intermittent monitoring instead, which has been shown to be just as effective in detecting problems, but without the associated risks. You can choose a care provider that prefers a less technological approach, or give birth in an environment where EFM is not routinely used, such as a birth center or at home. You do not have to accept any risk you are not comfortable taking. Take your birth into your own hands — know your rights and know your limits.
Ina May’s Guide to Childbirth (Gaskin, 2003)
Listening to Mothers Survey (2005)