Effect of Dexamethasone on Antepartum Cardiotocography

Abstract

Objective: The purpose of this study was to evaluate the effect of dexamethasone on fetal heart rate parameters using the standard dose regimen. Study Design: A prospective cohort study conducted in the Maternity Department, Suez Canal University hospitals. Sixty- eight pregnant women with gestational age between 28 and 34 weeks were recruited. Patients received 4 doses of dexamethasone 6 mg every 12 hours for threatened preterm delivery due to preterm premature rupture of membranes, placenta previa or history of preterm labor. Computerized cardiotocography was recorded for 60 minutes on day 0 (before dexamethasone administration), day 2 and day 4 after administration. Cardiotocography monitoring was performed between 11 am and 1 pm to avoid diurnal rhythm of fetal heart rate. Outcome measure included changes in fetal heart rate accelerations, variability and fetal movements following dexamethasone injection. Results: Sixty-eight patients were enrolled in the study. Fetal heart rate accelerations (P=0.0001), short-term variation (P=0.01), episodes of high variation (P=0.003) and fetal movements (P=0.0001) were significantly reduced on day 2 after dexamethasone. No significant changes were found on baseline fetal heart rate (P=0.18), long-term variation (P=0.1) and number of decelerations (P=0.1). All parameters returned to baseline values on Day 4 after administration. Conclusion: Dexamethasone induces transient suppression of fetal heart rate parameters on day 2 after administration that mimics fetal compromise. Awareness of this phenomenon is important to avoid iatrogenic delivery of preterm fetuses.