Betamimetics in fetal distress: randomised controlled trial. Effect of dexamethasone and betamethasone on fetal heart rate variability in preterm labour: a randomised study.
The objective of the study was to investigate if a single dose of Hexoprenaline administered to patients diagnosed as having fetal distress improves neonatal outcome and whether there are any side effects and complications related to hexoprenaline injection. Patients with fetal distress diagnosed by electronic fetal heart rate monitoring with a gestational age of 35 weeks or more in active labor were eligible. Once the decision to deliver the patient by Cesarean section was made, patients were approached and randomised by sealed opaque envelopes to hexoprenaline or control groups. Ten micrograms of hexoprenaline were administered intravenously to study patients. Main outcomes were cord blood gas values, Apgar scores, the need for resuscitation and admission to intensive care. There were no statistically significant differences in the main outcome measures between the two groups. Fewer babies in the hexoprenaline group had a pH of < 7.2 and a base excess of < -10, but this was not statistically significant. The fetal heart rate pattern was improved in significantly more patients after hexoprenaline administration than controls. In conclusion, despite the statistically significant improvement in fetal heart rate tracings, Apgar scores and blood gas values showed only a trend towards improvement in the hexoprenaline group. To compare the effects of betamethasone and dexamethasone on fetal heart rate in appropriately grown fetuses.
                Eighty-two pregnant women (97 fetuses) with preterm labour were randomly allocated to receive betamethasone (n=42) or dexamethasone (n=40) for fetal lung maturation in a nonblinded fashion. Computerised cardiotocogram (CTG) parameters were compared before, during and after treatment.
                A decrease in fetal heart rate variability was found with betamethasone but no significant changes were found with dexamethasone. Fetal heart rate variability returned to pre-treatment values within a week after cessation of treatment with betamethasone. Neonatal outcome was similar in the two groups.
                These findings might prove useful in the management of compromised fetuses with decreased fetal heart rate variability in which the CTG should be used together with other parameters to assess fetal wellbeing during corticosteroid treatment. Dexamethasone may be preferable as the drug of choice since it was associated with significantly less alteration in fetal heart rate variability compared with betamethasone.
Betamimetic therapy appears to be able to reduce the number of fetal heart rate abnormalities and perhaps reduce uterine activity. However, there is not enough evidence based on clinically important outcomes to evaluate the use of betamimetics for suspected fetal distress.