Effect of dexamethasone on fetal heart rate variability, by non-invasive non-stress test tracing in preterm labour

Background: To analyse the effects of antenatal dexamethasone on fetal heart rate variability (fHRV), when administered to mothers between 30-37 weeks of gestation, at risk of preterm delivery and corroborate presenting maternal symptoms with mode of delivery and perinatal outcomes. Method: Prospective observational study conducted for 1 Year among pregnant women with gestation between 30 completed weeks to 36 weeks 6 days, with symptoms suggesting risk of preterm delivery. The sample size calculated was 52. Dexamethasone phosphate, 24 mg in 4 divided doses, was administered as intramuscular injections 12 hours apart. NST tracings were taken at three points-before first dose, one hour after first dose and one hour after the fourth dose. Chi-square test and Paired t test was applied, p<0.05 was considered statistically significant. Results: Strong correlation was found between antenatal dexamethasone administration and fHRV (p<0.05) which increased after administration of the first dose of dexamethasone compared to its value prior to administration. There was a further increase after the fourth dose. Conclusions: Dexamethasone is associated with increase in fHRV evident on non-stress test recordings, without significant decrease in baseline fetal heart rate.