Electronic fetal monitoring was introduced in the 1960s and 1970s without much clinical trial. Still, early studies suggested positive outcomes, and in particular led doctors to believe that the EFM could prevent fetal asphyxia, or interruptions of oxygen to the fetus. Since asphyxia was thought to cause cerebral palsy, doctors were eager to use the new technology, which seemed to promise them greater control over birth than ever before. By the late 1980s however, large-scale trials demonstrated no benefit from EFM. Further research confirmed that consensus, and it has been well-established science for more than 20 years that EFM does not improve obstetric outcomes. 

But if the science has been against EFM, cultural prejudices have been on its side—and that’s proved decisive.  Over the course of the twentieth century, and into the twenty-first, birth in the United States has been increasingly medicalized. In part that means there have been more interventions available, including drugs, Cesareans, monitoring, episiotomies, and other surgical options. But it also means that pregnancy has been reconceptualized “as a disruption to health that necessarily requires expert medical intervention, and thinking of pregnancy as primarily about health and illness,” according to Amy Mullin, author of Reconceiving Pregnancy and Childcare. Medical technology is seen as necessary, and the more medical technology that’s employed, the safer the birth is thought to be. So doctors are reluctant to put aside any tools, even if those tools have been shown not to work. 

There’s another reason for retaining EFM: fear of malpractice. Doctors worry that if they stop using fetal monitors, they’ll be held liable for anything that goes wrong.