Clinical Inquiries

How does electronic fetal heart rate monitoring affect labor and delivery outcomes?

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EVIDENCE-BASED ANSWER

CONTINUOUS ELECTRONIC FETAL MONITORING (EFM) REDUCES THE RISK OF NEONATAL SEIZURE BY 50% compared with intermittent auscultation (IA) (strength of recommendation [SOR]: A, systematic review of randomized controlled trials [RCTs]).

EFM increases the incidence of cesarean section by 66% and the incidence of operative vaginal delivery by 16% (SOR: A, systematic review of RCTs). It has no effect on the rates of cerebral palsy or neonatal mortality (SOR: A, systematic review of RCTs).

An estimate from a Cochrane meta-analysis suggests that a cohort of 628 women receiving EFM could expect to experience 1 less neonatal seizure and 11 more cesarean sections compared with IA controls.

Evidence summary

Continuous EFM is designed to detect early fetal hypoxia and thereby decrease neonatal morbidity and mortality compared with IA. IA is defined as auscultation of the fetal heart rate for at least 60 seconds every 15 minutes during the first stage of labor and every 5 minutes during the second stage of labor.

A decrease in seizures, but not deaths or cerebral palsy
A 2006 Cochrane systematic review examined 12 RCTs (with >37,000 women) that compared continuous EFM with IA.1 Continuous EFM reduced the risk of neonatal seizure by 50% (relative risk [RR]=0.50; 95% confidence interval [CI], 0.31-0.80), but had no effect on the rate of neonatal death (RR=0.85; 95% CI, 0.59-1.23) or development of cerebral palsy (RR=1.74; 95% CI, 0.97-3.11).

Reduction of seizures was consistent across all trials. However, a subgroup analysis of high-risk pregnancies (advanced maternal age, diabetes mellitus, chronic hypertension, renal disease, preeclampsia, cardiac disease, renal disease, previous delivery of a low-birth-weight infant) didn’t find a statistically significant decrease in seizures.

Cesarean deliveries rise, regardless of patient risk status
Continuous EFM raised the rates of cesarean delivery (RR=1.66; 95% CI, 1.30-2.13) and instrumental vaginal deliveries (RR=1.16; 95% CI, 1.01-1.32). The increased rate of cesarean section in the EFM group was consistent regardless of clinical risk status (low- vs high-risk women). One additional cesarean section was performed for every 58 women monitored continuously. For “high-risk” women, 1 additional cesarean section was performed for every 12 women monitored continuously.1

Cesarean section rates varied widely among the individual trials (2.3%-35%). Analysis suggested that studies with higher baseline rates showed the greatest increases with continuous EFM. The rate for all studies combined was just 4.3%; 69% of patients included in the meta-analysis were contributed by the Dublin trial, which had an average cesarean rate of 2.3%.1 By comparison, the US Division of Vital Statistics reported a cesarean rate of 32.3% in 2008.2

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