1Junior Resident, Dy Patil Pune. Mobile: 9494831655. Email: ruk.sri123@gmail.com
2*HOD, Dy Patil Pune. Mobile: 9767505311. Email: drhemantdeshpande@gmail.com (Corresponding Author)
Background: Late preterm birth (34–36⁺⁶ weeks of gestation) accounts for a significant proportion of preterm deliveries and is associated with increased neonatal morbidity. Antenatal corticosteroids such as dexamethasone are widely used to enhance fetal lung maturity in pregnancies at risk of preterm birth. However, corticosteroids are known to cause transient alterations in fetal physiology, which may affect fetal surveillance parameters such as non-stress test (NST) and fetal heart rate (FHR). Understanding these effects is essential to avoid misinterpretation of fetal well-being and unnecessary obstetric intervention, particularly in late preterm labour.
Objectives: To evaluate the effect of antenatal dexamethasone administration on NST reactivity and fetal heart rate parameters in women with late preterm labour.
Methods: This prospective observational study was conducted over six months at a tertiary care teaching hospital and included 100 pregnant women between 34 and 36⁺⁶ weeks of gestation presenting with spontaneous or threatened preterm labour. All participants received intramuscular dexamethasone 6 mg every 12 hours for four doses. NST and FHR monitoring were performed before dexamethasone administration and subsequently at 12, 24, and 48 hours after the first dose. Parameters assessed included baseline FHR, variability, accelerations, decelerations, and NST reactivity. Data were analyzed using descriptive statistics, paired t-test, and chi-square test with SPSS version 26.
Results: The mean maternal age was 26.3 ± 3.7 years, and the mean gestational age was 35.2 ± 0.7 weeks. At baseline, 84% of NSTs were reactive. A significant increase in baseline FHR was observed at 24 hours post-dexamethasone (138.6 ± 6.4 bpm vs 145.2 ± 7.1 bpm; p < 0.01). There was a significant reduction in moderate variability (82% to 55%) and accelerations (76% to 58%) at 24 hours (p < 0.05). NST reactivity decreased to 62% at 24 hours but improved to 80% by 48 hours. No significant change in decelerations was observed.
Conclusion: Antenatal dexamethasone administration in late preterm labour resulted in transient and reversible changes in NST and FHR parameters, peaking at 24 hours and resolving by 48 hours. Awareness of these physiological effects is crucial to prevent misinterpretation of fetal surveillance and avoid unnecessary obstetric interventions.
Keywords: Antenatal; Dexamethasone; Fetal heart rate; Late preterm labour; Non-stress test corticosteroids.
How to cite this article: Chittampally SR, Deshpande H. Effect of Dexamethasone on NST and FHR in Late Preterm Labour. Int J Drug Deliv Technol. 2026;16(13s): 264-271. DOI: 10.25258/ijddt.16.13s.29
Source of support: Nil.
Conflict of interest: None