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Antenatal betamethasone and fetoplacental blood flow

1999; Elsevier BV; Volume: 354; Issue: 9174 Linguagem: Inglês

10.1016/s0140-6736(05)66329-5

1474-547X

Lia D. E. Wijnberger, C. M. Bilardo, Kurt Hecher, R. H. Stigter, Gerard H.A. Visser,

Birth, Development, and Health

We agree with Euan Wallace and Lesleigh Baker1Wallace EM Baker LS Effect of antenatal betamethasone administration on placental vascular resistance.Lancet. 1999; 353: 1404-1407Summary Full Text Full Text PDF PubMed Scopus (101) Google Scholar that a reduction in the vascular resistance in the placental bed is not automatically beneficial to the growth-retarded fetus. A reduction in the placental resistance may, assuming that no increase in cardiac output occurs, lead to impaired cerebral perfusion or reduced blood flow to other organs. However, this effect is unlikely, because the incidence of periventricular haemorrhage and necrotising enterocolitis is reduced after corticosteroid treatment.2Crowley PA Antenatal corticosteroid therapy: a meta-analysis of the randomized trial, 1972 to 1994.Am J Obstet Gynecol. 1995; 173: 3223-3235Summary Full Text PDF Scopus (767) Google ScholarThe study by Wallace and Baker is limited to the reappearance of end diastolic flow rather than any improvement in the flow velocity waveform. We did a prospective longitudinal multicentre study in fetuses with severe intrauterine growth retardation. Doppler studies of the umbilical artery were done at least once each week and the frequency increased to at least twice weekly when blood-flow redistribution was documented. Serial measurements were available from 45 fetuses that had received corticosteroids. Data were expressed as Δ values, based on the normal values for the pulsatility index (PI) of Harrington and colleagues.3Harrington K Carpenter RG Nguyen M Campbell S Changes observed in Doppler studies of the fetal circulation in pregnancies complicated by pre-eclampsia or the delivery of a small-for-gestational-age baby. I. Cross-sectional analysis.Ultrasound Obstet Gynecol. 1995; 6: 19-28Crossref PubMed Scopus (96) Google Scholar Day 0 was the day before corticosteroids were given. From each fetus, one measurement was selected randomly for any of the subsequent days. Thus, 16 values were available on day 1, 12 on day 2, nine on day 3, five on day 4, and three on day 5. The median values on day 2 and 3 were the lowest, but subsequent analysis by Kruskal-Wallis non-parametric ANOVA test showed no significant differences in ΔPI between the median values of day 1 to day 5. Paired measurements were available between day 0 and day 1 (n=21), days 0 and 2 (n=18), days 0 and 3 (n=22), days 0 and 4 (n=19), and days 0 and 5 (n=22). Differences in ΔPI were not significant (Wilcoxon signed-rank test).Our findings do not confirm the observations of Wallace and Baker. On the basis of our results, we postulate that their observation may be attributable to the physiological variation in doppler recorded flow velocity waveforms from the umbilical artery. We agree with Euan Wallace and Lesleigh Baker1Wallace EM Baker LS Effect of antenatal betamethasone administration on placental vascular resistance.Lancet. 1999; 353: 1404-1407Summary Full Text Full Text PDF PubMed Scopus (101) Google Scholar that a reduction in the vascular resistance in the placental bed is not automatically beneficial to the growth-retarded fetus. A reduction in the placental resistance may, assuming that no increase in cardiac output occurs, lead to impaired cerebral perfusion or reduced blood flow to other organs. However, this effect is unlikely, because the incidence of periventricular haemorrhage and necrotising enterocolitis is reduced after corticosteroid treatment.2Crowley PA Antenatal corticosteroid therapy: a meta-analysis of the randomized trial, 1972 to 1994.Am J Obstet Gynecol. 1995; 173: 3223-3235Summary Full Text PDF Scopus (767) Google Scholar The study by Wallace and Baker is limited to the reappearance of end diastolic flow rather than any improvement in the flow velocity waveform. We did a prospective longitudinal multicentre study in fetuses with severe intrauterine growth retardation. Doppler studies of the umbilical artery were done at least once each week and the frequency increased to at least twice weekly when blood-flow redistribution was documented. Serial measurements were available from 45 fetuses that had received corticosteroids. Data were expressed as Δ values, based on the normal values for the pulsatility index (PI) of Harrington and colleagues.3Harrington K Carpenter RG Nguyen M Campbell S Changes observed in Doppler studies of the fetal circulation in pregnancies complicated by pre-eclampsia or the delivery of a small-for-gestational-age baby. I. Cross-sectional analysis.Ultrasound Obstet Gynecol. 1995; 6: 19-28Crossref PubMed Scopus (96) Google Scholar Day 0 was the day before corticosteroids were given. From each fetus, one measurement was selected randomly for any of the subsequent days. Thus, 16 values were available on day 1, 12 on day 2, nine on day 3, five on day 4, and three on day 5. The median values on day 2 and 3 were the lowest, but subsequent analysis by Kruskal-Wallis non-parametric ANOVA test showed no significant differences in ΔPI between the median values of day 1 to day 5. Paired measurements were available between day 0 and day 1 (n=21), days 0 and 2 (n=18), days 0 and 3 (n=22), days 0 and 4 (n=19), and days 0 and 5 (n=22). Differences in ΔPI were not significant (Wilcoxon signed-rank test). Our findings do not confirm the observations of Wallace and Baker. On the basis of our results, we postulate that their observation may be attributable to the physiological variation in doppler recorded flow velocity waveforms from the umbilical artery.