Short-Term Effects of Betamethasone Administration on Fetal Heart Rate Patterns in Preterm Contraction

Preterm labor is a leading cause of neonatal morbidity and mortality worldwide. Antenatal corticosteroid therapy, particularly betamethasone, is widely used to improve neonatal outcomes.

To evaluate the short-term effects of maternal betamethasone administration on fetal heart rate variability using nonstress test (NST) tracings in preterm labor.

A prospective study was conducted on 62 pregnant women with preterm contractions between 28-34 weeks of gestation admitted to St. John's Medical College Hospital. Participants received two intramuscular doses of betamethasone (12 mg each, 12 hours apart). Serial cardiotocography recordings were performed at baseline and at 12, 24, 36, 48, 60, 72, and 84 hours after administration. NST parameters assessed included baseline FHR, beat-to-beat variability, accelerations, and decelerations. Data were analyzed using ANOVA and paired proportion tests, with significance set at P < 0.05.

Betamethasone administration was associated with a transient reduction in baseline FHR and beat-to-beat variability, most pronounced at 24-36 hours postadministration, with subsequent normalization by 72 hours (P < 0.0001). Accelerations also decreased initially but recovered over time, while decelerations remained absent across all recordings.

Maternal betamethasone causes temporary, reversible alterations in fetal heart rate variability and accelerations without adverse perinatal outcomes.