Acetaminophen for Fetal Tachycardia: a Randomized Pilot Trial

The most common cause of fetal tachycardia is maternal fever. Fetal tachycardia often precedes the maternal fever, and fetal tachycardia confounds the interpretation of electronic fetal monitoring (EFM), increasing the rate of cesarean delivery for non-reassuring fetal status (NRFS). Our hypothesis is that treatment of fetal tachycardia with acetaminophen will significantly lower maternal body temperature and significantly lower baseline fetal heart rate (FHR). The importance is that interpretation of EFM will improve, thus allowing for a decrease in cesarean delivery for NRFS.

This trial is a randomized, non-placebo controlled, assessment of whether acetaminophen can lower maternal temperature and baseline fetal heart rate in laboring patients with fetal tachycardia. Term singleton cephalic pregnancies in active phase labor (spontaneous or induced) with fetal tachycardia will be recruited. Patient will be excluded for: Exclusion criteria (prior to randomization): Acetaminophen allergy Clinical chorioamnionitis Maternal fever Non-reassuring fetal status (NRFS), which is the designation for fetal heart rate abnormalities requiring cesarean delivery Previous cesarean delivery Multifetal gestation Breech presentation Known fetal anomaly Known contraindication to vaginal delivery Primary outcome measures are: Maternal body temperature (oral) 90 minutes after treatment Baseline FHR Secondary outcome measures are: Temperature difference before and after treatment Rate of cesarean delivery Rate of determination of NRFS Rate of subsequent development of maternal fever Rate of diagnosis of clinical chorioamnionitis Rate of neonatal sepsis Power calculation Internal data collection at our institution of 53 patients showed a mean decrease in temperature of patients in labor with fever receiving acetaminophen is 0.3 degrees C measured an average (mean) of 90 minutes after administration of acetaminophen. Mean oral temperature before acetaminophen was 38.32, SD 0.33. Mean oral temperature after acetaminophen was 38.03, SD 0.85. Sample size calculation shows that 27 patients are needed in each group to show significant difference using alpha 5% and beta 50%.

Fever in labor is identified,consenting and randomization occurs, either acetaminophen is given or no medication is given, then 90 minutes later maternal temperature is recorded.

Maternal temperature difference before randomization and 90 minutes after randomization in degrees Centigrade

Non-reassuring fetal status is when cesarean delivery or operative vaginal delivery (forceps or vacuum) are performed for fetal heart rate abnormalities.

Rate of subsequent development of maternal fever, i.e., the number of participants who developed fever.

Rate of diagnosis of clinical chorioamnionitis, i.e., the number of participants who developed chorioamnionitis.

Inclusion Criteria: Term pregnancy Singleton pregnancy Pregnancy with cephalic presentation Pregnancy in active phase labor Fetal tachycardia Exclusion Criteria: Acetaminophen allergy Clinical chorioamnionitis Maternal fever Non-reassuring fetal status or fetal heart rate abnormalities requiring cesarean delivery Previous cesarean delivery Multifetal gestation Breech presentation Known fetal anomaly Known contraindication to vaginal delivery