Visual interpretation of the effect of maternal betamethasone administration on the fetal heart rate pattern.
This study was performed to interpret visually the effect of maternal betamethasone administration on the fetal heart patterns in women at risk for preterm delivery. These effects had previously only been described using computer analysis. It was a retrospective study of 54 women who had received two doses of betamethasone 12 hours apart and had fetal heart tracings before, and on the first and second days after steroid administration. The primary outcome measure was change in short-term variability and secondary outcome measures were change in long-term variability, baseline fetal heart rate, accelerations and decelerations. Inter-observer variation of fetal heart rate variability was also measured. Betamethasone caused a significant reduction in short-term variability 1 and 2 days after administration. There was no effect on baseline fetal heart rate or on variable decelerations. A transient decrease in fetal heart rate accelerations was observed on the first day after steroid administration but not on the second day. Inter-observer variability was good between the two observers (GJH and BVI). In most clinical settings, surveillance of fetal wellbeing is achieved most commonly by visual inspection of the fetal heart tracings and not by computer analysis. Clinicians should be aware of the effects of betamethasone on these tracings when considering interventions and/or other tests of fetal wellbeing.