What cEFM Stands For in Obstetrics
cEFM stands for continuous electronic fetal monitoring, a method of continuously recording fetal heart rate and uterine contractions during labor using external or internal transducers. 1
Definition and Technical Components
Continuous electronic fetal monitoring (cEFM or continuous EFM) refers to the uninterrupted electronic recording of fetal heart rate patterns and their temporal relationship to uterine contractions throughout labor 1
The technology uses either external transducers placed on the maternal abdomen or internal monitoring devices (fetal scalp electrode for heart rate, intrauterine pressure catheter for contractions) 1
This differs fundamentally from intermittent auscultation, which involves periodic Doppler assessment of fetal heart rate at defined intervals (every 15-30 minutes in active labor, every 5 minutes during pushing) 1, 2
Historical Context and Current Use
Continuous EFM was developed in the 1960s specifically to screen for fetal hypoxia, hypoxic-ischemic encephalopathy, cerebral palsy, and impending fetal death during labor 1, 3
By 2002, approximately 85% of live births in the United States (3.4 million out of 4 million) were monitored using continuous EFM, making it routine practice in North American hospitals 1
Clinical Evidence and Outcomes
The only demonstrable benefit of continuous EFM is a reduction in neonatal seizures (number needed to treat = 661), with no significant reduction in cerebral palsy or neonatal mortality compared to intermittent auscultation 1, 4
Continuous EFM has a false-positive rate of 99% because the events it screens for (hypoxic-ischemic encephalopathy, cerebral palsy, fetal death) have very low prevalence 3
The widespread use of continuous EFM has increased cesarean delivery rates (number needed to harm = 20) and instrumental vaginal births (number needed to harm = 33) without improving overall perinatal outcomes 1, 4
Appropriate Clinical Applications
For low-risk pregnancies: Structured intermittent auscultation is equivalent to continuous EFM and is the preferred method, as it avoids unnecessary interventions while maintaining equivalent neonatal outcomes 2
For high-risk pregnancies: Continuous EFM is appropriate and indicated for conditions including 1, 2:
- Fetal growth restriction or intrauterine growth restriction
- Abnormal umbilical artery Doppler findings
- Meconium-stained amniotic fluid
- Maternal fever or chorioamnionitis
- Neuraxial analgesia or epidural placement
- Abnormalities detected on intermittent auscultation
Common Pitfalls
Avoid routine admission tracings in low-risk pregnancies, as they increase interventions (epidural use, continuous monitoring, fetal scalp testing) without improving neonatal outcomes 1
Do not confuse antepartum surveillance (which uses intermittent non-stress tests lasting 20-40 minutes, performed weekly or twice-weekly) with intrapartum continuous monitoring (which is uninterrupted throughout active labor) 2, 5
Continuous EFM may adversely affect labor by decreasing maternal mobility, physical contact with partners, and time with labor nurses compared to intermittent auscultation 1