Improvement of cardiac function in fetuses with growth restriction following antenatal betamethasone administration: fact or artifact?

Abstract

Introduction Use of corticosteroids for fetal lung maturation has reduced the perinatal mortality/morbidity from prematurity related complications. There is a paucity of studies evaluating the effect of steroid administration on the fetal circulation and cardiac function in fetal growth restriction (FGR). The aim of the study was to assess changes in fetal Doppler indices and cardiovascular function in pregnancies complicated with FGR after administration of betamethasone. Methods This was a prospective study conducted in a tertiary care research center between July 2017 and May 2018. Pregnant women with FGR between 28 and 36 weeks’ gestation, who were scheduled to receive betamethasone (two doses of 12 mg, 24 h apart) were recruited. Fetal cardiovascular function in fetuses FGR was assessed immediately before first dose and once between 6 and 24 h after the second dose of betamethasone by the same operator. Wilcoxon matched-pairs signed-rank test or paired t-tests were used to compare parameters before and after corticosteroid exposure. Results Fifty cases with FGR were evaluated before and after administration of betamethasone, at mean gestational age of 34.6 ± 2.0 weeks. Fetal heart rate (148.78 ± 9.10 versus 144.73 ± 9.61, p < .001), left heart myocardial performance index ([MPI], 0.66 ± 0.06 versus 0.55 ± 0.09, p ≤ .001) and right heart MPI (0.65 ± 0.04 versus 0.63 ± 0.04, p .016) showed improvement after steroids. Left heart isovolumic relaxation and contraction indices along with ejection time of both sides showed a small but statistically significant improvement (p < .001), but other fetal cardiac functional and Doppler indices remain unchanged after steroids. Conclusions Fetal heart rate, cardiac MPI, left sided isovolumic indices showed an improvement after betamethasone administration. Follow up studies are needed to ascertain whether these effects persist in the long term and to determine whether these are beneficial to a growth restricted fetuses.